The Embryology of Chlamydoselachus 555 



figure 11, showing similar organs). On this page, above Dean's sketch, is the statement 

 "Ovid, [uterus?] of r. [side] dilated [through a length of] 340 mm.". Two pages away is 

 another and more elaborate sketch of a non^gravid right oviduct (previously referred to) 

 in which the uterus is labelled 25 mm. wide and 280 mm. long. 



None of these specimens (except Nishikawa's) had ova in their uteri, and none of 

 these uteri save those figured by Deinega and by Smith give us any clear idea of the size 

 and the degree of distention attained before the young are born. However, some under' 

 standing of the degree of this dilation may be had by considering the number of eggs and 

 embryos (with their measurements) that have been found in some gravid uteri. Earlier in 

 this article some of these data have been used for other purposes but for completeness they 

 will have to be repeated here. 



Number of Eggs and Embryos in Gravid Right Uterus. — From two men only do we 

 get firsthand data as to uterine embryos and their yolk sacs. Nishikawa introduces us 

 to the subject briefly. But from Dean's notebook and from specimens brought back from 

 Japan or sent thence to him, we get a good idea of the great size of eggs and embryos and 

 of the uterine distention to which they give rise. 



Nishikawa (1898) says "The right oviduct [600 mm. in total length] is very much 

 distended . . when as many as 12 eggs [his upper limit] each 110-120 mm. long are con^ 

 tained in it". Some of his eggs had embryos — the largest only 60 mm. long. He also 

 speaks of having other eggs 65 to 75 mm. in shortest diameter and from 102 to 124 mm. in 

 longest measurement. He figures in natural size an egg (Text'figure 4 herein) 67 x 100 mm. 

 in an egg shell measuring 137 mm. including the processes. 



Of large uterine embryos, Dean lists 14 specimens ranging from 165 to 390 mm. 

 (6.6 to 15.35 in.). Of these only two have measurements of the yolk sacs set down. 

 However, Dean brought from Japan and deposited in the zoological museum of Colum' 

 bia University three embryos with yolk sacs, and in the American Museum six embryos 

 with yolk sacs. From the Museum of Comparative Zoology, there has been loaned a large 

 embryo on its yolk sac. This was presented by Dr. Dean in 1912. The measurements of 

 these embryos with yolk sacs give one a full conception of the distention they would 

 produce. They will be considered later, but it may be well first merely to list the embryos 

 without yolks. 



Dean's notebook records 12 such fishlets. To these I have added a specimen (190 

 mm.), in the collection here, from which the yolk has been removed. The measurements 

 of these little fishes are from snout to tail'tip. These 13 range from 165 to 352 mm. 

 (6.5 to 13.8 in.) as follows— 165, 175 (2 specimens), 185 (2), 190, 195, 205, 210, 240, 250, 

 317, 352 mm. 



To get a better idea of the distention of the gravid right uterus one must consult 

 table I wherein are listed embryos ranging from 170 to 390 mm. (6.7 to 15.35 in.). These 

 sit on yolk sacs whose diameters (measured in the lines of length and depth of the fish) 

 vary from 67 x 55 mm. (fish, 327 mm.), to 111 x 100 (fish, 331 mm.), to 73 x 51 (fish, 374 

 mm.). With from 8 to 12 of these contained in the slender body of this snake-like {anguine 

 eus) shark, one can judge the enormous enlargement of uterus and abdomen. 



