ELASMOBRANCHII. 81 



jaws minute, obtuse. Nostrils inferior. Gill-openings moderate, 

 inferior. Spiracles wide, behind eye. Dorsal fins large, without 

 spines, first nearly opposite ventrals. Caudal well developed, 

 bent upward. A fold along each side of tail. Pectorals mod- 

 erate, front margin quite free and not reaching to head. 



Large shark-like rays, with the disk gradually passing into the 

 tail, found in mbst warm seas about sandy shores. A single 

 existing genus, the exact batoid prototype of the Pristiophoridae. 

 The fossil species of this family are all provisional, being known 

 chiefly by rostral teeth, fragments of the rostrum, detached ver- 

 tebras, etc., thus rendering the descriptions too imperfect for 

 final determination. They have been referred to three genera, be- 

 sides to the existing Pristis. 



Genus PRISTIS Linck. 



Pristis Linck, Mag. P. Naturg. Gotha, VI, 1790, p. 31. Type Squalus pristis 



Linnseus, monotypic. 

 Pristobatus Blainville, Bull. Soc. Philomath. Paris, 1816, p. 121. Type Pristis 



antiquorum Latham, first species. 

 Pristibaiis, Pristobatis, auct. 

 Myriosteon Gray, Proc. Zool. Soc. Lond., 1864, p. 163. Type Myriosteon 



higginsi Gray, monotypic. (Proposed as "probably indicating a new 



group of Echinodermata," though really based on one of the hollow 

 - cartilaginous rostral rods of Pristis.) 

 Pristiopsis Fowler, Proc. Acad. Nat. Sci. Phila., 1905, p. 459. Type Pristis 



perrotteti Muller and Henle, designated. 

 Eopristis Stromer, Beitr. Pal. Oester. Ung., XVIII, 1905, p. 52 (16). Type 



Pristis (Eopristis) reinachi Stromer, monotype. 



Characters of the genus expressed in those of the family. 

 About eight existing species are known, and about 19 extinct 

 species have been described. 



Pristis ambIvODOn Cope. 



Pristis amblodon Cope, Proc. Boston Soc. Nat. Hist., XII, 1869, p. 312. New 

 Jersey Eocene Greensand. 

 Hussakof, Bull. Amer. Mus. Nat. Hist. N. Y., XXV, 1908, p. 34, fig. 11 

 (types). 



Rostral teeth well compressed. Front margin convex, and sur- 

 face smooth. Hind margin convex and smooth. Length of 

 smaller example (imperfect) 26 mm. 

 6 GEOL 



