Here he did the work which was subsequently published in 1878 in his Monograph of the Development of Elasmobranch Fishes, and which constituted the most important addition to vertebrate morphology since the days of Johannes Muller.
This is particularly clearly seen in the case of the anterior part of the head of Elasmobranch and probably of other vertebrate embryos, where all the mesoderm present is derived from the anterior part of the neural crest (Quart.
A tubular orifice communicating with the gill cavity of certain ganoid and all elasmobranch fishes.
Defn: That division of elasmobranch fishes which includes the sharks.
A preliminary account of the development of the Elasmobranch Fishes.
A Monograph on the development of Elasmobranch Fishes.
A Monograph on the development of Elasmobranch Fishes.
It is very difficult to prove anything definitely about these nerves, but, for reasons stated in my work on Elasmobranch Fishes, I am inclined to regard them as anterior roots of one or more spinal nerves.
The arrangement of the ingrowth through the choroid slit in Elasmobranchii (Scyllium) has been partially worked out, and so far as is at present known the agreement between the Avian and Elasmobranch type is fairly close.
Apart from the absence of the pronephros the points which deserve notice in the Elasmobranch excretory system are (1) The splitting of the segmental duct into Wolffian (mesonephric) and Muellerian ducts.
In the Amniota they also bear at their extremity a thickened cap of epiblast, which may be compared with the epiblastic fold at the apex of the Elasmobranch fin.
I cannot bring my own observations into accord with his as to the structure of the Elasmobranch testis.
The only essential difference between the two embryos arises from the roof of the segmentation cavity being formed in the Elasmobranch embryo of lower layer cells, which are absent in the Amphibian embryo.
It apparently develops in all the Amniota nearly on the Elasmobranch type, as a solid rod, primarily derived from the somatic mesoblast of the intermediate cell mass (fig.
This difference no doubt depends upon the greater quantity of yolk in the Elasmobranch ovum, and a similar distribution of the lower layer cells is found in Acipenser and in Petromyzon.
Footnote 5: I employ here the same letters to indicate the stages as in my "Monograph on Elasmobranch Fig.
Its inner outline is somewhat irregular, and it is imperfectly divided into lobes, which form the commencement of structures nearly equivalent to the nests of the Elasmobranch ovary.
In my monograph on the development of Elasmobranch Fishes an account was given of the earliest stages in the development of the primitive ova, and I now take up their development from the point at which it was left off in that work.
Balfour, Monograph on the Development of Elasmobranch Fishes, plate 20, figs.
The development of the Elasmobranch ovary has recently formed the subject of three investigations.
Huxley holds that the mesopterygium is the proximal piece of the axial skeleton of the limb of Ceratodus, and derives the Elasmobranch fin from that of Ceratodus by the shortening of its axis and the coalescence of some of its elements.
It appears to me probable that the ova in all Elasmobranch Fishes have at some period of their development the two membranes described at length for Scyllium.
Compare also my Monograph on Elasmobranch Fishes, note on p.
In most Fishes they are in no way connected; but in some Elasmobranch embryos, more especially in that of Torpedo, they are connected together at their first development by a line of columnar epiblast cells.
At the stage spoken of in my monograph on Elasmobranch Fishes as stage L, the ovarian ridge has a very small development, and its maximum height is about 0.
Balfour, "Monograph on the Development ofElasmobranch Fishes," p.
Traquair regards them as highly aberrant sharks, or, more exactly, as being derived, like the Chimaeras, from a primitive Elasmobranch stock.
But only in the latter regard could they have differed more widely from the primitive Elasmobranch or Teleostome, if it be admitted that in the matter of dermal structures they may be clearly separated from the Chimaeroid.
Müller, Williamson, and Steenstrup--had been struck with the resemblance existing between the placoid scales and the teeth of Elasmobranch fishes.
A Monograph on the Development of Elasmobranch Fishes, London, 1878.
Traquair suggests that Thelodus arose from the original elasmobranch stock; that by the fusion of scutes such a form as Drepanaspis occurred, and, with still further fusion, Pteraspis.
Thus adrenalin obtained from the elasmobranch fishes will produce in the highest mammal all the effects known to occur upon stimulation of the nerves of its sympathetic system.
He is still an advocate of the elasmobranch origin of all these earliest fishes, and claims that the latest discoveries of the Silurian deposits (Thelodus Pagei) and other members of the Coelolepidae confirm this view of the question.
This suborder was formed for the reception of Cladoselache, an Elasmobranch found in the Lower Carboniferous of Ohio[32].
In support of this view it may be argued that the paired and unpaired fins are often identical in structure, and that some Elasmobranch embryos do show a ridge running between the pectoral and pelvic fins.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "elasmobranch" in a variety of sentences. We hope that you will now be able to make sentences using this word.
