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552 Bashford Dean Memorial Volume 



Unfortunately, after more than 30 years in preservative, the condition of the speci' 

 mens in the American Museum is such that the internal structure of the shell glands can- 

 not be studied advantageously. 



THE UTERUS 



In all viviparous sharks, the hinder part of the oviduct is enlarged into a more or less 

 capacious sac in which are received the fertilised ova when they pass downward from the 

 shell gland. Here the embryos undergo their development and here they are retained 

 until the shells are cast off and until the young are so far developed that they may be 

 passed out into the sea to fend for themselves. To fit the uteri for these purposes, they 

 are much modified in various sharks and rays, and marked differences arise in the function- 

 ing of the right and left organs. This asymmetrical functioning we shall now study in 

 Chlamydoselachus. 



Right Uterus Functional 



Since the oviducal apparatus of a shark is bilateral, one might expect to find the two 

 oviducts equally developed in Chlamydoselachus. And so they are in sexually immature 

 females such as Smith's 1398-mm. fish (Text-figure 10). In a footnote to Nishikawa's 

 article (1898), Goto says, ''When no eggs are contained there is no perceptible difference 

 in size between the two oviducts." Such also is the condition shown in Momose's 

 figure (1938) and much more clearly in the sketch sent me (Text-figure 9). This condition 

 is rather unexpected in this fish when one views the 80-mm. eggs contained in both 

 ovaries (Text-figure 9). That this condition is not always and necessarily true when eggs 

 are absent from the oviducts is seen in Smith's drawing (my Text-figure 11) of the oviducts 

 of his 1550-mm. specimen. This fish was almost sexually mature but like Goto's specimen 

 was nonbreeding. The right oviduct (Text-figure 11) was noticeably larger than the left, 

 and the ovaries contained growing eggs up to 17 mm. in diameter. Presumably the right 

 uterus only in this fish was destined to be functional. 



Our earliest information concerning the inequality of development of right and left 

 oviducts in the frilled shark comes from Samuel Garman (1885), the man who first dissected 

 Chlamydoselachus. In his specimen, which had been partially eviscerated, the anterior 

 portions of the oviducts (about 12 in. long) remained as shown in his drawing (Text-figure 

 8 herein). But of the hinder end he was fortunately able to say — ''A piece left at the 

 cloaca showed one of the ducts greatly distended, possibly with young that had hatched 

 within it [or which had been removed before the specimen came to him]. Only one of 

 these tubes had been in use". 



Next comes Collett (1897) who states that in his 1910-mm. fish each oviduct was 

 900 mm. long, and that "Towards their upper [lower ?] ends each expands to a uterus-like 

 sack of which the right is somewhat larger than the left; both contained immature eggs". 

 As noted above in the section on the ovaries, Collett or his translator got his identification 

 of organs mixed, and here as there I have supplied the correction in brackets. His state- 

 ment that both oviducts (the right being better developed) contained eggs, even if im- 

 mature, is significant. It will be referred to later. 



