626 Bashford Dean hiemona] Volume 



— i.e. the shark is cloak-gilled (Greek, Chlainys. a cloak). Paired latero-sensory canals are 

 found on each first gill-cover and extend far on the throat region toward the symphysis of 

 lower jaw. The hindmost ot these canals are continuations or the ones seen on the first 

 pair of gill-covers in the dorsal aspect. The short gill-filaments are visible. 



The stout pectoral fins with, their strong bases look ""finished"". Beginning between 

 them and extending backward are the tropeic tolds or bilge keels with therr deep median 

 groove. One wishes that this excellent drav^Tng portrayed the ventral surface clear 

 back to the tip of the caudal fin. 



As noted, Dean's '"List"" calls ror ""Adult, photo oi head lat. it ventral"". These 

 I have found, old and faded. The specimen, firom which these photographs were made, had 

 been mutilated in both gill-regions — the parts of particular interest just here — and ap- 

 parently had suffered partial maceration. Furthermore, the shrunken gill-flaps and the 

 distorted gill-filaments indicate that they had undergone considerable drying. These 

 photographs portray gill-region conditions unlike what are tound m the eleven figures of 

 heads and of whole fish reproduced by Gudger and Smith ' 1933 '. Such conditions were 

 not found m a single one of the srs specimens m the ^American \Iuseum studied by Smith 

 (1937j. nor are they portrayed in any of Dean's four figures reproduced herein as plate VI. 

 It is e\'ident that the photographs do not portray a normal specimen as it appeared in life 

 and that they possess no scientific \^lue whatever. There are no notes to teU us by whom 

 they were taken, why they were made, nor why they were included in Dean's records. 

 They will not be reproduced in this article. 



EXTERX.\L GILL-FILAMEXTS IX CHLAMTDOSELACHUS 



Before concluding this study of the breeding habits and external embryonic develop- 

 ment of Chla-mydoselachns, the matter of its external gills must be taken up. These, as 

 indicated above, are commonly round in the embryos but very rarely in adults. In the 

 embr\'os they are in origin totally unlike the external gills tound present m Crossopterygii, 

 Dipnoi, and in .Amphibia, and are considerably different m length and profusion from the 

 external gills figured and described in the embryos of many species ot elasmobranchs. 

 Chlamydoselachus is the only shark known to me to possess in the adult stage, even occa- 

 sionally, short external gill-filaments. This matter of external gill-filaments is so important 

 that it must be considered carefully. 



EXTERX.^L GILL-FIL.'WIENTS OF THE EMBRYOS 



The embryos of all non-placental viviparous sharks and rays known to me have long 

 external gills. The eggs of these elasmobranchs have thin diaphanous shells, through 

 which uterine fluids readily penetrate. These fluids are milk-like secretions ot the uterine 

 mucosa and ser\'e as food ror the growing embryos, which absorb this tood through their 

 long filamentous gills. It has been indicated above that the relatively thick shells of 

 Chlamydoselachus are burst by the growmg embryo, are cast off into the uterus (Figure 11, 



