62 ORDERS, SUB-ORDERS, AND FAMILIES. 



Selaehoidei. (ELASMOBRANCHII.) PLATES xxviii. to xxxi. Nos. 223 



to 237. 



CARCHARIID^E. Body cylindrical. Two dorsals, first without spine and 

 placed above space between pectorals and ventrals ; anal present. Eye 

 with nictitating membrane. Mouth crescent shaped, inferior ; snout 

 slender and conical, or hammer-shaped. Teeth hollow when fully 

 grown. Carcharias, 222 ; Galeus, 223 ; Mustelus, 225 ; Zygcena, 224. 



LAMNID^E. Body cylindrical. Two dorsals, first without spine and placed 

 above space between pectorals and ventrals ; anal present. Eye with- 

 out nictitating membrane. Mouth crescent-shaped and inferior. 

 Teeth solid when fully grown. Alopecias, 227 ; Lamna, 226 ; Selache, 228. 



NOTIDANID^. Body cylindrical. One dorsal only, spineless, placed 

 above space between ventrals and anal. No nictitating membrane. 

 Mouth crescent-shaped and inferior. Gill openings six or seven. 

 Notidanus, 229. 



SCYLLIID^:. Body cylindrical. Two dorsals, first without spine and 

 placed above or behind ventrals ; anal before, below, or behind 

 second dorsal. No nictitating membrane. Spiracles distinct. 

 Mouth semi-circular or angular, inferior. Teeth small, and several 

 rows in use at once. Pristiurus, 232 ; Scyllium, 230, 231. 



SPINACID^E. Body cylindrical. Two dorsals ; anal absent ; pectorals not 

 notched at base, and not prolonged forwards. No nictitating 

 membrane. Mouth inferior, slightly arched, with loag, deep oblique 

 groove on each side. Spiracles present. Gill openings narrow. 

 Acanthias, 233 ; Centrina, 235; Echinorhinus, 236 ; Lcemargus, 234. 



SQUATINID^;. Body depressed and flat. Two dorsals ; anal absent ; 

 pectorals large with base prolonged forward. Spiracles behind the 

 eyes. Mouth anterior. Teeth conical and pointed. Gill openings 

 wide and lateral. Rhina, 237. 



