108 



64. Snout with a detached pair of cephalic fins ; spine on the 



tail ; sides of head free from pectoral fin. Myliobatidje 

 — LVI. {Tijpe, Whip-tail Ray.) 

 „ Snout otherwise constructed. 65. 



65. Pectorals not extending to snout ; two dorsals on tail. 



Rhixobatid.^ — LII. 

 „ Pectorals extending to, or confluent at, extremity of snout. 



66. Spine on tail ; tail without lateral longitudinal folds. Try- 



go nid^ — LV. {Type^ Stingaree.) 

 „ Two dorsals on the tail ; tail with a longitudinal fold on each 

 side; no serrated caudal spine. Rajid^ — LIV. {Type, 

 Skate. 



67. Head without barbels ; sometimes with ])ouch under throat ; 



fresh-water. Petromyzoxtid.i^— LVII. {Type^ Lam- 

 prey.) 

 „ Cirri on each side ot fissure-like mouth ; marine. Cirrsotomi 

 — LVIII. {Tyjje, Lancelet.) 



68. Ventral fins present. Pegasid.i: — XXXIX. 

 „ No ventral fins. Syngnathid^ — XL. 



69. The elements of a spinous dorsal and ventral fins generally 



present. Sclerodermi— XLI. 

 „ No spinous dorsal. No ventrais. Pectoral fins. A soft 

 dorsal, caudal, and anal fin. Gymnodoxtes — XLII. 



70. Prseoperculum armed. TRiGLiD.^:,part — VII (Cottid^.) 

 „ Preeoperculum not armed. Sclenid.!: — IX. 



