NOTIDANI. 



149 



Sub-order 1, 



NOTIDANI. 



With six or 

 seven branchial 

 apertures and a 

 small spiracle 

 with one dorsal 

 fin without spine. 

 Vertebral col- 

 umn imperfectly 

 segmented. Cau- 

 dal fin without a 

 pit at its root ; 

 without labial 

 fold and nictitat- 

 ing membrane. 



Fam. 1. Chlamy- 

 doselachidae.* 



15 od y eel-like; 

 mouth anterior ; 

 nasal opening 

 divided and on side 

 of head ; lateral 

 line as an open 

 iiroove on the body, 

 but closed (with 

 openings left) on 

 the head ; with 

 six gill openings 

 and six branchial 

 arches ; opercular 

 fold (first gill- 

 cover) free across 

 the isthmus ; the 

 palatoquadrate is 

 orbital process of 

 hyomandibular ; 



Fig. 88. — A. CMamydoselachus angui- 

 neus Garman ; B. side view of the 

 head of the same (after Garman). 



not articulated with the post- 

 the skull and there is a large 

 notochord unconstricted pos- 

 teriorly ; teeth similar in both jaws, each with 

 three slender, curved cusps separated by a pair 

 of rudimentary denticles on a broad base ; vivi- 

 parous. Chlamydoselachus Garman, from the deep 

 sea, 5-6 feet. Japanese seas, Atlantic and 

 Arctic. 



* Garman, Bull. Mus. Zool. Harvard Colleye. 12, 

 1S85. 



