l.l.ST OF FISH. 23 



Plagiostomata, Mull. Abh. Akad. Berl. 1836. Mag. Zool. \ Bot. 



i. 405. 

 Pisces cartilaginei, Ray, Syn. Pise. 28. 

 Selaciens (Plagiostornes) Cuv. Reg. An. 2 ed. ii. 383. 

 Selaca (Selaque), Blain. Bull. Soc. Phil. 112, 1826. 

 Selacha (Plagiostoma), Bonap. Selach. Fulula Analilica, 1838, 4to. 

 Plagiostomi, De Kaij, Nat. Hist, of New York, 348. 



M. De Blainville (Bull. Soc. Phil. $• Jour, de Phys. 260, 1816), 

 proposed to form the flat-bodied cartilagineous fish into a sub-order, 

 which he called Selaca, and divided it into three genera : — 1. Rata. 

 — 2. Squutina. — 3. Squalus. 



Mullerand Henle {Mag. Nat. Hist. ii. 1838) separate the Plagios- 

 tomi into two orders, 1 Skates (Raite), 2 Sharks (Squali) ; the former 

 characterized by the existence of a peculiar cartilage arising from 

 the nasal part of the skull and extending towards, and even meeting 

 to form the anterior part of the crest of the pectoral-fin : there is 

 no trace of this cartilage in the sharks. 



Synopsis of Families. 



1. Squali. — Skull without any frontal cartilage ; branchial open- 

 ings lateral. 



1. Scylliad^e. — Body elongate, subcylindrical ; pectoral-fins 

 moderate; lateral part of the dorsal-fins over or behind the abdomi- 

 nal-fin. 



2. Squalid.e. — Body elongate, subcylindrical; pectoral-fins mo- 

 derate ; lateral dorsal one or two first before the abdominal-fin. 



3. Squatinad.e. — Body rather depressed; pectoral-fins very large. 



2. Raii. — Skull with a peculiar frontal cartilage from the nasal, 

 extending in front and meeting, forming the front crest of the pec- 

 toral-fin ; branchial-opening inferior. 



4. CristisidjE. — Body elongate, gradually tapering into the tail. 



5. Raid^e. — Body much depressed, broad, abruptly ending in 

 a slender tail. 



