516 PISCES (CARTILAG.) PLAGIOSTOMI. [RAIA. 



205. R. clavata, Linn. (Thorn-Back.) Teeth sharp 

 in the male ?, blunt in the female : skin rough ; studded 

 with large osseous tubercles terminating in strong spines ; 

 one, three, or five, rows of such tubercles on the tail. 



R. clavata, Linn. Syst. Nat. torn. i. p. 397. R. Rubus, Block, Ichth. 

 pi. 84. (Male.) R. clavata, Id. pi. 83. (Female.) R. clavata, 

 Don. Brit. Fish. vol. n. pi. 26. Turt. Brit. Faun. p. 111. Mont, 

 in Wern. Mem. vol. n. p. 416. Flem. Brit. An. p. 170. Blainv. 



Faun. Franc,, p. 33. Thorn-Back, Penn. Brit. Zool. vol. in. p. 93. 

 pis. 11, and 12. Id. (Edit. 1812.) vol. m. p. 122. pis. 13, and 14. 

 La Raie bouelee, Cuv. Reg. An. torn. n. p. 398. 



LENGTH. From two to three feet; sometimes more. 



DE SCRIPT. (Form.) General form resembling that of the R. macu- 

 lata: snout short, and rather obtuse: mouth wide, transverse: teeth 

 larger than in the above species, and not so closely compacted; set in 

 oblique rows ; each with a broad round head, terminating, in the male ?, 

 in a strong curved point ; in the female, all blunt, with scarcely any trace 

 of a point or cutting edge : nostrils, eyes, and spiracles, much as in the 

 R. maculata : body rather thick, convex above ; the whole of the upper 

 surface extremely rough with minute hooked spines and asperities, be- 

 sides which are a greater or less number of large osseous tubercles, each 

 terminating upwards in a strong hooked spine, or tooth-like process, very 

 sharp at the extremity ; these spinous tubercles, which are of an oval 

 form, and very broad at the base, are scattered about in rather an irre- 

 gular manner, and very variable in number ; almost always one or two 

 above the eyes, and a row down the middle of the back, continued along 

 the ridge of the tail ; also one or two on each side of the dorsal series 

 about the middle ; sometimes three complete rows on the back, and three 

 or five on the tail ; occasionally, especially in large fish, the under surface 

 of the body is studded with tubercles as well as the upper ; more rarely 

 the tubercles are almost wanting altogether : tail a little longer than the 

 body, depressed, rather stout, and very rough with minute asperities inde- 

 pendently of the spinous tubercles ; two finlets near its extremity, much 

 as in R. maculata, besides the rudiment of a caudal : pectorals and vent- 

 rals the same as in that species. (Colours.) Variable: generally bluish 

 gray above, tinged with reddish brown; the whole sparingly sprinkled 

 with large, but ill-defined, whitish spots: beneath white. A variety 

 sometimes occurs, shewing more or less appearance of an ocellated spot 

 on the middle of each pectoral. 



Common as this species is on all parts of the coast, its true charac- 

 ters, at least those which distinguish the sexes, are involved in a little 

 obscurity. Montagu was led to regard the R. Rubus of authors, in which 

 the teeth are sharp, as the male of R. clavata, in which they are blunt, 

 from the circumstance of his not being able to discover a female of the 

 former, nor a male of the latter, species. As far as my own observa- 

 tion goes, which, however, has been but limited, it confirms Montagu's 

 opinion. I have never seen a male Thorn-Back with blunt teeth, but 

 I have seen, in the collection of Mr. Yarrell, two fish perfectly similar in 

 every respect, excepting that in one, a male with long ventral append- 

 ages, the teeth were sharp, in the other, a female, the teeth were blunt. 

 Tnese I was led to regard as the sexes of the common Thorn-Back. Yet 

 both Risso and Blainville speak of the sexes of the R. clavata, without 

 any allusion to the teeth being otherwise than blunt, in the male, as well 



