At that time spermatogenesis starts for the first time and the weight of the baculum increases from less than 30 milligrams to more than 52 milligrams.
Although goldmani bears some external resemblance to lepida, the cranial characters mentioned above and the size and shape of the baculum show that goldmani is best arranged as a member of the albigula group.
The baculum of goldmani differs slightly from that of albigula in having a less downwardly curved shaft and in having a less pronounced median dorsal depression at the proximal end.
Measurements (in millimeters) of the mature baculum (fig.
The baculumof goldmani, when compared with bacula and with figures of these bones in Burt and Barkalow (Jour.
The baculum (os penis) of Eozapus is known to me only from Vinogradov's (1925) figures of the dorsal and lateral aspects.
The baculum of Zapus differs from that of Eozapus as follows: base less expanded horizontally; shaft slenderer; distal end less spade-shaped except in Z.
Baculum with tip lanceolate (not spade-shaped) and tip less than 0.
Baculum with tip spade-shaped and tip wider than 0.
Structural progressiveness is postulated for the species that has the simplest (in this instance specialized) baculum and smallest fourth upper premolar.
Values obtained from several measurements of the skull and baculum allow for ready recognition of the two species.
The baculum has a characteristic size and shape according to the species, and the following significant measurements of the structure were taken: Greatest length.
The baculum of the chipmunks of western North America.
The general shape and dimensions of the baculum (os penis) provide characters of taxonomic value for the species of Zapus (see figs.
Venter yellowish or buff; tip of baculum more than 30 per cent of length of shaft; shaft of baculum not widened at base.
Size large; general tone of upper parts dark reddish brown; sides Tawny or Ochraceous Tawny; baculum large, as in E.
Size large; over-all tone of upper parts brownish gray; sides Ochraceous Buff; baculum as in E.
Over-all tone of upper parts less grayish; underside of tail lighter; skull narrower and shorter; baculum shorter.
However, in the skull and baculum these specimens resemble E.
Size large; general tone of upper parts dark; base of baculum widened; outermost dorsal dark stripe barely discernible or lacking; skull rarely shorter than 34.
Dorsal light and dark stripes distinct; over-all tone of upper parts less grayish (more tawny); tip of baculum less than 38 per cent of length of shaft in adult specimens.
General tone of upper parts darker, more reddish and less grayish; ventral surface of tail more tawny; skull and baculum of same size and proportions.
Underside of tail lighter; general tone of upper parts grayer; sides lighter; skull and baculum of same size and proportions.
Size large; over-all tone of upper parts grayish brown; baculum large, as in E.
General tone of upper parts ochraceous; underparts strongly buffy; tip of baculum in adult specimens, more than 30 per cent and less than 38 per cent of length of shaft.
Size medium; pelage dark; sides dark; narrow cranial breadth; baculum distinguishable from that of any other species (E.
General tone of upper parts darker; braincase significantly narrower; baculum shorter and markedly wider at base.
Size medium; dorsal dark stripes tawny; crown Drab-Gray; baculum of same proportions as in E.
Size large; sides Capucine Yellow; antiplantar surface of hind feet Raw Sienna; postauricular patch grayish white; baculum as in E.
Size medium; general tone of upper parts grayish; baculum one of the largest of species.
However, having only the structure of the baculum as evidence additional to that summarized by Hall (op.
This difference permits any specimen which has an associated baculum to be readily identified to species.
Size large; sides Clay Color; antipalmar and antiplantar surfaces of feet Cinnamon-Buff; baculum as in E.
General tone of upper parts, sides, underside of tail, and feet, all darker in coloration; baculum shorter and proportionally twice as wide at base.
Size medium; sides light; general tone of upper parts light; baculum one of largest in species.
The characters of the baculum are an aid, but not in and of themselves an adequate basis, for determining the natural relationships of the groups of species.
I doubt that the similarity in the baculum is significant, at least in this one instance.
A study of the baculum in the genera Perognathus and Dipodomys.
I find that the difference in shape and size of the baculumbetween the subspecies of D.
Grinnell placed these two species in separate groups; Burt on characters of the baculum alone placed D.
The structure of the baculum most closely resembles that of E.
The Baculum in the Chipmunks of Western North America BY JOHN A.
Banff and Canmore in western Alberta, recourse to the baculum is almost necessary.
In the youngest specimens that I have taken, the M3 and m3 have not yet erupted and there is no wear on P4 and p4; nevertheless, the baculum in these specimens has nearly an adult configuration and size.
In the species of the subgenus Neotamias the proximal part of the baculumis termed the shaft, and the distal upturned part is termed the tip.
Preparation and preservation of the baculum of mammals.
In the chipmunks the baculum varies but little with age.
The large size of the keel of the baculum in this species is distinctive among chipmunks of western North America.
Lateral view of right side, unless otherwise indicated, of the baculum in each of the species of chipmunks (subgenus Neotamias) of western North America: 1.
Dearden (1958) studied the baculumin two Asiatic species of Lagurus, in six subspecies of Lagurus curtatus of North America, and in six other species of microtines of other genera.
The baculumshows no noteworthy resemblance to that of any other species of North American Microtus; on the other hand the differences between M.
The baculum in Microtus ochrogaster--orientation and variation with age.
The baculum in lemmings as a group cannot then be considered more primitive than in voles as a group, although the voles are usually considered to be more advanced.
The method described above leaves the baculum intact within the glans penis; therefore its orientation can be determined relative to the thick walled urethra and the thin walled dorsal artery that extends onto the dorsal side of the baculum.
The baculum in microtines consists of an elongate stalk, having a laterally, and to a lesser extent dorsoventrally, expanded base and an attenuate distal shaft.
The baculum in the Microtinae more closely resembles the baculum in the Cricetinae of the Old World than in the Murinae, or than in any other rodents known to me.
The terminal part of each penis including the baculum imbedded in the glans penis was removed in its entirety and placed in a vial.
Shape of baculummost resembled that of Ochrotomys and Calomys.
Internal structures such as hyoid apparatus, auditory ossicles, and baculum remained almost unchanged, as for example in Calomys now living in South America.
The baculum in the chipmunks of western North America.
The resemblance in cranial morphology between Peromyscus and Baiomys is judged to be the result of such a convergence of habitus and the baculum in Baiomys is thought to reflect relationships more accurately than does the skull.
In each of the two species, individual and geographic variation in the baculum is slight; its length varies insignificantly according to age.
In general shape, as well as in possession of an anterior knob and the position of the expanded posterior wings, the baculum of C.
Altamira, however, has a baculum of the same shape as in angustapalata (this same specimen is one of the three from there in which the re-entrant angle of the M1 is deep).
The shape of the baculum among specimens of micropus is highly variable and bacula of specimens from different localities frequently are slightly different (see Fig.
Keeping in mind that the baculum in the North American sciurids can be classified into six structural groups, as given above, the baculum in each of the subgenera Eutamias and Neotamias and in the genus Tamias is briefly described.
In Marmota the baculum is greatly enlarged at the posterior end and forms a shieldlike surface.
The base (proximal end) of the baculum is broad, and some species have a winglike process extending dorsally and partly covering a longitudinal groove.
The baculumin Tamias, in general plan of structure, resembles that in Spermophilus (=Citellus) and Cynomys of the tribe Marmotini Simpson.
There is a knoblike process on the crest at a point three fourths the length of the baculum from its base.
From this study of variation of thebaculum in American chipmunks, it can be extrapolated that the baculum in the Asiatic Eutamias would show little individual variation in structure.
In discussing the baculum in Eutamias and Tamias, it seems desirable to do so in the light of the structure of the baculum in other sciurids.
The baculum in Glaucomys is the most distinctive of that of any American sciurid.
The type of baculum in Spermophilus is spoonshaped with a ventral process that is spinelike or keellike.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "baculum" in a variety of sentences. We hope that you will now be able to make sentences using this word.
