The Embryology of Chlamydoselachus 531 



that later the finished sketches were made from these and from preserved specimens. 



Finally, I have received from Dr. Naohide Yatsu, of Tokyo Imperial University, 

 information which confirms the conjectures above and adds further to our knowledge of 

 the authorship of these excellent drawings. Dr. Yatsu was associated with Dr. Dean 

 on the first visit to Japan, and afterwards at Columbia University, where he was a student 

 of Dean's and later an assistant in the Department of Zoology. 



On the matter in question, Yatsu writes that at Misaki, Dean made sketches in 

 pencil and in color from living embryos of Chlamydoselachus. Indeed among Dean's 

 relicta is such a color sketch of the internal organs of a female Chlamydoselachus. As to 

 the finished drawings, Yatsu is sure that the color figures were made from Dean's color 

 sketches and the pencil drawings from Dean's sketches and also from preserved material. 

 These were done in Tokyo in 1905 under Dean's supervision at the Zoological Institute of 

 the University by Isaburo Kuwabara, the Institute draftsman. This is also the testimony 

 of Yatsu's colleague. Dr. Tanaka. 



VIVIPARITY (OVOVIVIPARITY) IN CHLAMYDOSELACHUS 



All elasmobranchs (sharks and rays), whether oviparous or viviparous, have internal 

 impregnation and fertilization. To effectuate this, the male is provided with intromittent 

 organs, the claspers. These are modified portions of the hinder and inner part of each 

 pelvic fin, which are inserted into the cloaca of the female and served to hold her fast and 

 to transmit the seminal fluid. 



The preponderant evidence is that oviparity was the original method of reproduction 

 in elasmobranchs. It persists today in certain sharks and skates, which extrude eggs en' 

 closed in horny envelopes provided with tendrils by means of which they become at' 

 tached to marine objects. In Chlamydoselachus the large egg is enclosed in a keratinoid 

 capsule provided at each end with a process which varies greatly in form and structure. 

 It is sometimes blunt but in many instances it is long, curved, and frayed at the apex into 

 tendrils (Figures 2, 7 and 13, plate I). If these encapsuled eggs were found outside the 

 body of the fish, one would surmise that these curved processes serve as organs of attach' 

 ment. But egg and capsule are retained within the uterus even after the developing 

 embryo has burst the shell, as will be shown later. 



Thus in this shark, the presence of the egg shell with curved horns or frayed pro' 

 cesses plainly indicates that the ancestors of Chlamydoselachus practiced oviparity. Yet in 

 the frilled shark, possessing so many primitive characters, there prevails the most highly 

 specialized form of reproduction — viviparity, or more properly ovoviviparity as will be 

 explained later. This is another instance of the strange admixture of primitive and 

 specialized characters found in Chlamydoselachus as pointed out by Smith in his study of 

 the anatomy (1937). 



That the fish is viviparous must have been known to Ludwig Doderlein, who, in the 

 years 1879-1881, made an extensive collection of Japanese fishes. These were brought in 

 1881 to Vienna, and among them were two specimens of Chlamydoselachus taken in 



