The Embryology of Chlamydoselachus 567 



Shortly after the egg enters the oviduct, fertilization, encapsulation, and segmentation 

 take place, followed later by gastrulation and the formation of the embryo. It is not 

 known at what stage in the development of the growing embryo the capsule is burst, 

 thrown off the yolk sac, and expelled from the uterus into the sea. But it must be long 

 before the embryo attains the stage shown in Figure 11, plate I. However, we are here 

 concerned with the early stages in which the egg is still encapsuled. These eggs occur in 

 two distinct forms — as ellipsoidal and as round eggs. 



ELLIPSOIDAL EGGS OF THE FRILLED SHARK 



This form and shape of the encapsuled egg of Chlamydoselachus seems to be the 

 typical one. At least, save for four round eggs portrayed by Dean, all eggs figured by all 

 authors are ellipsoidal. This is true even of eggs freed from their capsules. Thus Brohmer 

 (1909) figured without capsule an ellipsoidal egg 110 mm. long with an embryo of 75 mm. 

 As drawn the yolk mass is 108 x 60 mm. And Garman (1913) portrayed a shelMess egg 

 98 X 56 mm. with a 59'mm. embryo on it. Neither figure will be reproduced here since, 

 lacking details, they are of no particular value in this study. 



Dean figured in color (Figure 50, plate V) a shell-less ellipsoidal egg 95 x 56 mm. 

 with an embryo 39 mm. long. Then, among his miscellaneous Chlamydoselachus records, 

 I have found a water-color sketch of a 55'mm. embryo on a yolk sac measuring 122 x 69 

 mm. This sketch, which is rather crude, was not made by Dean and was not intended for 

 reproduction. The egg, from which the capsule had been removed, was taken off Okinose 

 (Sagami Sea) in December, 1906. The references to these eggs without capsules are 

 merely to show that the ellipsoidal form is the predominant one. Attention will now be 

 directed to the capsules of these great eggs. 



As portrayed by Dean, ellipsoidal encapsuled eggs seem to be of two kinds — normal 

 and abnormal or at least unusual. These, as figured by him and by other investigators, 

 will now be studied. 



NORMAL ELLIPSOIDAL ENCAPSULED EGGS 



The first encapsuled egg of Chlamydoselachus ever figured may be taken as an ex' 

 ample of the normal egg of this type. The description and figure are from Nishikawa 

 (1898). His material came from seven female specimens from the Sagami Sea. These 

 fish contained from 3 to 12 eggs each — all ellipsoidal in form. His statement follows and 

 evidently has to do with eggs in very early stages since he speaks of their having blastO' 

 derms on them. He also had eggs of the same type with early embryos as will be now 

 shown. Here is Nishikawa's description: 



The egg is ellipsoidal, and varies between 65-75 mm. in its shorter diameter and 102-124 

 mm. in its longer diameter, the measurements being made in physiological solution of salt (Figs. 

 1 & 2) [Fig. 1 = Text-figure 4 herein]. It bears a stumpy excrescence at one end and a sHghtly 

 recurved flattened process, about 35 mm. long, at the other. The capsule is light brown and 

 transparent. The space between the capsule and the yolk sac is, in earlier stages, very in- 

 significant, being confined mostly to the two poles of the eggs, and is filled with the white, 

 which is very fluid. The yolk is of a pinkish color, and the yolk-sac is very delicate. 



