XOTIDANI. 



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- 

 d o selac hidae.* 

 Body eel-like; 

 mouth anterior ; 

 nasal opening 

 divided and on side 

 of head ; lateral 

 line as an open 

 groove on the body, 

 but closed (with 

 openings left) on 

 the head ; with 

 six gill openings 

 and six branchial 

 arches ; opercular 

 fold (first gill- FIG. 88. A. Chlamydoselachus angui- 

 neus Garman ; B. side view of the 



head of the same (after Garman ). 



x f 

 cover) free across 



the isthmus ; the 



palatoquadrate is not articulated with the post- 



orbital process of the skull and there is a large 



hyomandibular ; 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 College, 12, 

 1885. 



