RHINOPTERA. 443 



Rhinopteridae. 



Body, head, and pectorals united in a broad lozenge-shaped disk in which 

 t he development of the pectorals is greater in the anterior half. A pair of rosl ral 

 fins, not joined in front of the skull and not continuous at the sides of the head 

 with the pectorals. Teeth broad, angular, flat, in pavement, median series 

 broadest in most species. Eyes prominent, lateral. Spiracles large, behind the 

 eyes, opening laterally. Cranium prominent. Tail long, slender, whip-like, 

 with a dorsal fin above the basal portion and with aberrated spine farther back. 



Rhinoptera. 



Rhinoptera Voigt, 1832, Thierreich, 2, p. 525. 

 Zygobatis Agass., 1838, Rech. poiss. foss., 3, p. 79. 

 Rhinoptera Gill, 1S65, Ann. N. Y. lye, 8, p. 136. 

 Mylorhina Gill, 1S65, Ann. N. Y. lye, 8, p. 136. 

 Micromcsus Gill, 1865, Ann. N. Y. lye, 8, p. 136. 



Disk broad ; head moderately prominent. Pectorals not continuous along 

 the sides of the head to the snout. Rostral fins detached from the pectorals, 

 forming a produced, free and flexible lobe in front of each orbit, not produced in 

 front of the middle of the head. Anterior nasal valves confluent in a broad flap, 

 free behind and at the sides. Skull broad, subtruncate, depressed to a rather 

 sharp edge in front of each eye, deeply notched at the fontanel. Eye round, 

 pupil erect. Tail long, slender, with dorsal fin and a serrated spine above the 

 basal portion. Teeth tessellated, angular, in five or more rows, 5-19, median 

 commonly wider. 



Tropical and temperate seas. 



Fossil species of the genus have been recorded from the Lower Eocene, the 

 Miocene, and the Pliocene. 



Teeth in seven rows ; skin smooth 



median teeth 5-7 times as wide as long, next row 2\, others decreasing in 



width regularly quadriloba (page 444) 



median teeth 3-6 times as wide as long, next outer 2-3, outer two rows at 



each side as wide as long .... lalandii (page 445) 

 median teeth 3-5 times as wide as long, next outer half as wide, outer two 



rows at each side as wide as long . . javanica (page 446) 

 median teeth 3 times and next outer 2 times as wide as long, outer rows 



narrower steindachneri (page 446) 



