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Bashford Dean hiemorial Volume 



shell, however, still projected into the hinder part of the shell gland, and when drawn out 

 this was found to be soft and gelatinous with prolongations which were evidently tendrils 

 in the process of making. These were broken off in removing the egg, but they were 

 placed in their normal position as shown in the photograph reproduced as Text'figure 21. 

 This egg was '"non-fertile". 



From another female dissected on this day, I got an egg capsule with a pair of pro- 

 cesses 55 mm. long, and on another capsule one process 120 mm. long. These eggs were 

 undersi2;ed and probably infertile — though this unfortunately was not specifically noted 

 as it was for other eggs below standard limits of size. My notes record five other cases 

 from specimens dissected June 19. Some shells had processes on the posterior (i.e. last 



formed) end, a few had them on the anterior (first-formed) end, 

 though here the capsule was generally ' 'blunt" or rounded. The 

 posterior end of the capsule still in the shell gland or just out of it 

 was always soft, light in color and often translucent. That end 

 first formed and first out of the gland, the anterior end, was 

 always hard, dark in color, and noted as ""finished". These in- 

 fertile eggs were plainly wind eggs comparable to that of Chlamy 

 doselachus shown in Figure 51, plate V. 



From these facts the only conclusion 

 that can be drawn is that in Gingly 

 mostoma the formation of these rudiment- 

 ary and very variable processes indicates 

 that they are vestigial structures inherited 

 from oviparous ancestors whose egg shells 

 had tendrils for holdfasts. Everything 

 points to the face that the ovoviviparous 

 shark Ginglymostoma is on its way toward 

 becoming a truly viviparous one. 



No dissections and no direct obser- 

 vations of the formation of the egg capsule 

 of Chlamydoselachus have ever been made. 

 But several scientific men on being asked 

 which end of the egg capsule of the frilled 

 shark was finished first (was the older) 

 have unhesitatingly answered "the blunt 

 end", and when asked why have answered 

 that "It looks finished" — and so it does, 

 while the end having the process looks 

 "unfinished". For these points contrast 

 the two ends of the capsule in Nishikawa's 

 egg (my Text-figure 4) and in Deans' 



Text-figure 21 

 Two typical egg capsules of the nurse shark 

 Ginglymostoma cirratum. The first, a wind egg, 

 has the rudiments of tendrils at the hinder end. 

 The second, a fertile egg, has the normal, blunt, 

 unfinished hinder end to its capsule. 

 Photograph by E. W. Gudger. 



