The Anatomy of Chlamydoselachus 497 



TABLE V. 

 CENOGENETIC CHARACTERS OF CHLAMYDOSELACHUS 

 Unusually elongate form of the body. 

 Weakness of the dermal fin rays. 



Bunching of the pelvic, dorsal and anal fins near the caudal. 

 Unusually large mouth, and very distensible oropharyngeal cavity. 



First pair of gill-covers enlarged, loose-fitting and frilled. They are continuous with a gular fold, unique 

 among sharks. 



Abdominal or tropeic folds, unique among vertebrates. 



Peculiar and imperfect hyostylism of the skull. The hyomandibular articular facet is very long, permitting 

 a gliding action. 



Jaws are unusually long, and begin far posterior to the cranium. 



Heterospondyly of the extreme caudal end of the vertebral column. 



Shortness and irregularity (fragmentation, displacement, fusion) of cartilaginous fin rays (radials). 



Infolding of the musculature of the ventral body wall in connection with the tropeic folds. 



Alleged absence of an intermandibular muscle innervated by a branch of the trigeminal nerve. 



Dorsal group of eye muscles much stronger than the ventral group. 



Presence of an accessory musculus rectus lateralis. 



All the recti muscles, save only a portion of the accessory rectus laterahs, take origin from the eyestalk. 



Pyloric vestibule sometimes a sharply defined division of the digestive tube. 



The middle intestine is expanded to form a bursa entiana. 



Right and left lobes of the liver extend the entire length of the body cavity. 



The gill-clefts are unusually large, and the respiratory surface afforded by the gills is great. 



The external spiracular openings are very small. 



Mesonephric duct, urinary sinus and urethral pore of the right side are often defective. 



In adult females, the genital organs of the right side are much better developed than those of the left side ; 

 the latter are probably not functional. 



The young are retained in the uterus until they reach an advanced stage of development. 



The anterior unpaired portion of the pericardio-peritoneal canal is very short and broad. The paired canals 

 often end blindly. 



Afferent branchial arteries are connected by a series of loops over the gill-slits. 



The connections between the acustico-lateralis elements of the fifth, seventh and eighth cranial nerves 

 show a tendency toward unification of the system. 



Peculiar mechanism by which the eyes may be protected in the absence of lids, 



