Jordan and Ercrnmnn. Fishes of North America. 67 



two sexes, and the male is usually provided with a differentiated patch of 

 spines on each pectoral. Species numerous; mostly of the Northern seas. 

 They are, on the whole, not very well known, and an analytical table 

 which would show their natural affinities can not be made out in the 

 present condition of our knowledge. There is considerable variety within 

 the genus, but the natural subgenera are yet to be defined. Thus far all 

 attempts at natural subdivision have resulted in failure. We are, there- 

 fore, forced to make a primary division on the unnatural character of the 

 geographical distribution of the species. The synonymy of some species is 

 still uncertain. The best account of the eastern species is that given by 

 Mr. Garman in Proc. Bost. Soc. Nat. Hist., 1874, 170, ct seq. Of this wo 

 have made large use in the following analysis, (raja, or raia, a ray, or 

 skate.) 



I. Atlantic species. 



a. Middle line of back and tail behind shoulders unarmed in the adult, with a row of spines 

 in the young; outline of disk before spiracles obtuse, without acute angle at tip of 

 snout; species with round dark spots. 



b. Teeth in about 50 series in each jaw ; size small. ERINACEA, 91. 

 bb. Teeth in about 90 series in each jaw; size large; usually a pectoral ocellus. 



OCELLATA, 92. 



aa. Middle line of back with a row of spines at all ages. 



c. Tip of snout rounded, very blunt, without marked angle. Skin very rough; color varie- 



gated. FYLLA:, 93. 



cc. Tip of snout with a more or less marked angle. 



d. Angle at tip of snout short, obtuse; teeth in 30 to 50 series. 



e. Body and tail armed with large bucklers, each with a radiated or stellate base. 



EADIATA, 94. 



ee. Body and tail armed with small, close-set, stellate spines; color dark brown 

 with irregular markings. PLUTONIA, 95. 



eee. Body and tail smooth or with small asperities. Larger spines on orbital re- 

 gion, back and tail; brownish, with lighter and darker spots. 

 /. Disk a little longer than broad. ACKLEYI, 96. 



ff. Disk a little broader than long. o UN ATA, 97. 



dd. Angle at tip of snout acute, moderately long. 



g. Spines on skin above scarcely stellate; teeth in 50 rows; color brown with 



darker markings. EGLANTEKIA, 98. 



gg. Spines on skin above small, their base stellate; teeth in about 40 rows; color 



brown, sometimes with 1 or 2 paler spots above. SENTA, 99. 



ddd. Angle at tip of snout much produced, blunt at tip; teeth in 30 rows. 



h. Skin nearly smooth, its spines few and small; color brownish, with paler spots. 



LjEVis, 100. 



II. Pacific species; median line of tail always with stronger spines. 



i. Snout acute or acuminate, more or less projecting beyond the disk, the rostral 



cartilage well developed. 

 j. Snout very long acuminate; usually no spines on median line of back in 



front of ventrals; interorbital space little concave. 



k. Snout tapering to a point; skin almost everywhere prickly above; color 



nearly plain brown. RHINA, 101. 



kk. Snout long, but bluntish at the tip; skin minutely prickly above, 



smoother than in preceding; 1 or 2 spines at center of back; color 



brown, with large rounded white spots above. BINOCULATA, 102. 



jy. Snout of moderate length, rather sharp, but shortish; color brownish; 



usually with 2 faint ocelli; interorbital space deeply concave; prickles 



on body rather small. 



