ACADEMY OF SCIENCES. 109 



I have myself seen specimens of large size in which the spot is as distinct 

 as in the young, and though I cannot say I have measured them, I feel 

 assured that one I saw in the aquarium at Woodward's Gardens about a 

 year ago was two feet across the fins; and that the one now there is about 

 eighteen inches. 



Moreover, the eye-like spot in the centre of the pectoral is anything but 

 obscure in the recent fish, it is most conspicuous. 



But this is not all. We have in our possession a fish (caught in San Fran- 

 cisco Bay,) which agrees in every respect with the description of R. batis in 

 the Brit. Mus. Cat. 



I subjoin the dimensions — 



INCHES. 



Width across pectorals 18.38 



Tip of snout to centre of posterior jaw 4.12 



anterior edge of anus ... 12.75 



orbit 4.12 



Tail to back of ventrals 8.75 



Inter-orbital space (width of) 1.37 



Width across ventrals 7.50 



Body and fins of a uniform slaty brown color. The difference in aspect 

 between this fish and the Uraptera or Raia binoculata is very great. 



Cenlropomus. Sp. ? 



Body oblong, compressed; head contained four and a half times in the total 

 length; outline of top of head nearly straight, slightly concave, ridges of up- 

 per surface prominent; depth increasing to origin of first dorsal, thence nearly 

 equal to root of second dorsal, thence decreasing gently to peduncle of tail. 

 First dorsal with eight spines — the first minute; the second about one-sixth 

 the length of the third; third, longest, very stout; fourth, fifth, sixth and sev- 

 enth rapidly decreasing; eighth, prostrate. Pectorals small, extending to 

 little more than the half length of the ventrals, which exce^i them in size. 

 First spine of anal very small ; second, long and stout; third, slender, but 

 slightly the longest. The orbit is slightly elliptical. Lower jaw protruding 

 beyond the upper; maxillary, when the mouth is closed, extending to a per- 

 pendicular from the centre of the pupil. Teeth nominal. Pre-operculum 

 strongly serrated. Color, when fresh, back to lateral line dark green, be- 

 coming lighter below, and whitish on the belly. Snout, green, yellow on the 

 sides. Iris, golden. Pectorals, lead-color, with green centre; ventrals, the 

 same. Caudal, lead-color in centre, with green margins. Dorsal, green, with 

 bluish stripe, and tipped with golden. Fin-formula, T>. 8\-fo; A.%. Branch- 

 iostegals, 7. The following are the principal dimensions of the specimen 

 presented: 



Ft. In. 



Total length, from tip of lower jaw to end of tail 1 5.5 



Length of head, from tip of upper jaw 3.88 



Tip of snout to origin of first dorsal 5.5 



