The zona radiata attains a very great development, and is generally provided with knobs of various shapes on its outer surface.
A zona radiata is generally (if not always) present in Elasmobranchii, but arises at a later period than the vitelline membrane (fig.
Externally to the zona radiata there may be observed a granular membrane irregular on its outer surface on which the cells of the discus are supported.
The formation of the zona radiata has been studied by Selenka.
In Reptilia precisely the same arrangements of the membranes are found as in Elasmobranchii, except that as a rule the zona radiata is relatively more important.
The zona radiata always disappears long before the ovum is ripe.
In the ripe ovum of the Herring there is a distinctly developed membrane external to the zona radiata which is probably the vitelline membrane.
Many observers have described prolongations of the follicle cells through the pores of the zona radiata in Aves, Reptilia and Teleostei.
Within the zona radiata a third and delicate membrane is occasionally found, especially when the ovum is approaching maturity.
In birds both vitelline membrane and zona radiata are present, but the latter atrophies early, leaving the former as the sole membrane when the egg is ripe.
The term zona radiata will be applied to perforated membranes of this kind.
The larva of Discina radiata has been described by Fritz Mueller (No.
The animals of Testacea, and the Radiata of the higher zones, are much more brilliantly coloured than those of the lower, where they are usually white, whatever the hue of the shell may be.
Report on the Mollusca and Radiataof the Ægean Sea, and on their distribution, considered as bearing on Geology.
Mollusca and Radiata existed before Vertebrata, and the progression from Fishes to Reptiles and Mammalia, and also from the lower mammals to the higher, is indisputable.
We have next the remarkable fact that the Radiata of Cuvier, the lowest and most plant-like of the marine animals, are comparatively slenderly represented, yet that there are examples of their higher as well as of their lower forms.
Pyriform bodies surrounding the zona radiata of the ovum, probably the remains of epithelial cells.
Externally to the zona radiata there may generally be observed a somewhat granular structure, against which the follicle cells abut, and I cannot agree with Waldeyer (loc cit.
In Reptilia[418] precisely the same arrangement is found as in Elasmobranchii, except that as a rule the zona radiata is relatively more important.
The inner one is the zona radiata with a typical radiately striated structure.
In Petromyzon, a zona radiata appears to be present[420], which is divided in the adult into two layers, both of them perforated.
The inner of the two perhaps corresponds with the membrane internal to the zona radiata in other types.
The zona radiatahas been made rather too thick by the artist.
I have not been able definitely to decide the relation of the zona radiata to the first formed vitelline membrane.
The stage of about the greatest development of both the vitelline membrane and zona radiata is represented on Pl.
A special internal differentiation of the zona radiatais apparently found (Eimer) in many Reptilia.
Both the vitelline membrane and the zona radiata are found in Raja, but in a much less developed condition than in Scyllium.
He says: "The radiata possess many points of affinity with the vegetable kingdom, and of these the circular arrangement of their parts is one of the most evident.
But though the term Radiata is applied to an extensive division, in which the members have many characteristics in common with each other, the ray-like form is not equally distinguishable in all.
Among the higher orders of the Radiata we meet with the strange Sea Cucumbers and the Sea Urchins, and the Star fishes; and among the lower orders the Sea Anemones, many forms of which are described and figured in these pages.
We know that the Infusoria, the polyps, and the Radiataonly live in the water; that the worms even only live some in the water and others in very damp places.
It will be noticed that he separates theRadiata (Radiaires) from the Polypes.
This is an anticipation of the division by Leuckart in 1839 of the Radiata of Cuvier into Coelenterata and Echinodermata.
The species, and even genera of all the early radiata and mollusks were exchanged for others long ago.
A new sub-kingdom, made out of part of the radiata of Cuvier.
My doubts, I remember, related to the rate of change of the Radiata in the Secondary formation, and of the Foraminifera in the oldest Tertiary beds.
Don's radiata and tuberculata, although considered to be the same species, were nevertheless founded on different forms of the cone.
A systematic arrangement follows, based on the evolution of the cone and seed from the comparatively primitive conditions that appear in Pinus cembra to the specialized cone and peculiar dissemination of Pinus radiata and its associates.
The group called Radiataby Cuvier, included, too, a number of animals which are widely separated from the "Zoophytes" in modern systems of classification.
The great French zoologist, Cuvier, gave the group name Radiata to animals of this kind.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "radiata" in a variety of sentences. We hope that you will now be able to make sentences using this word.
