2 1 6 Memoir Sears Foundation for Marine Research 



R.jenseni agrees so closely with R. hyperhorea in proportional dimensions and in 

 shape of disc and fins that detailed description in these respects would only be repeti- 

 tious. There is a median row of 24—3 1 large thorns on conspicuously radiate bases 

 from the nuchal region to the first dorsal fin, these becoming successively smaller and 

 increasingly crowded rearward along the tail, the total number decreasing somewhat 

 with growth ;^^ four large thorns on each shoulder on smaller specimen, 2—3 on larger; 

 one close to inner end of spiracle, one just in front of each orbit, and one close behind 

 it; a row of several small thorns around inner anterior margin of orbit in young but 

 not in older specimens; also on young, 2—3 rows of thorns of various sizes along 

 rostral ridge which are shed progressively with growth; disc also generally rough with 

 small prickles (In addition to the thorns) on small specimens except around posterior 

 margins of pectorals; the snout, the region between orbits, the anterior margins of disc, 

 a band across each pectoral, and a belt along either side of posterior part of mid-dorsal 

 ridge continuing prickly with growth; pelvics prickly on inner part but without thorns 

 (more or less thorny on R. hyperhorea); first and second dorsals with a few small prickles; 

 sides of tail with a dense prickly band from base to tip. Lower surface smooth.^* Teeth 

 56—66 above and below on specimens counted, loosely spaced in transverse series, 

 sharp-pointed in both sexes, as in R. hyperhorea (cf. Fig. 46 D with 44 D). 



Color. Upper surface (after many years' preservation in alcohol) plain light brown, 

 either grayish or of chocolate hue, darker along margins of fins. Ground tint of lower 

 surface brownish gray, grayish white, or perhaps pure white, but areas around cloaca 

 and over inner parts of pelvics of small specimens dusky, these dark areas expanding 

 over the abdomen with growth; outer margins of pectorals also brown in large speci- 

 mens. Conditions in the related species, R. hyperhorea (p. 210), suggest that the dark 

 markings on the lower surface may be widely variable in R.jenseni also. 



Remarks. R.jenseni was first reported and discussed as Raja granulata Goode and 

 Bean, 3' and our earlier accounts of it^^ were under that same name. But it seems prac- 

 tically certain that the Skate for which the specific name granulata was proposed orig- 

 inally^^ and the specimen that was figured subsequently under that name by its de- 

 scribers*" actually was a Raja laevis (p. 228). 



Si-ze. The largest specimen known (a female) was about 850 mm long (see Study 

 Material), suggesting that its maximum size is about the same as that for R. hyperhorea. 



35. Thirty-one thorns in the median row in the smallest R.jenseni seen but only 24 or 25 in the half-grown specimen; 

 a complete count could not be made for the largest specimen. 



36. The largest of the three listed specimens (see Study Material, p. 213) was described earlier by us (Bull. Mus. comp. 

 Zool. Harv., 68, 1927: 246; Canad. Atlant. Fauna, 12% 1934: 29) under the name R. granulata Goode and Bean 

 1879 as having minute rounded tubercles sparsely sprinkled over the lower surface of the disc. Re-examination 

 has shown, however, that Jensen's (Mindeskr. Steenstr. Fods. Kbh., 2 [30], 1914: 22, footnote) characterization 

 of it as perfectly smooth below was correct; doubtless the supposed tubercles (no longer to be seen or felt) were 

 merely grains of sand imbedded in the mucous. The specimen was in a good enough state to afford a detailed de- 

 scription when we first saw it, but it is now fragmentary. 



37. Jensen, Mindeskr. Steenstr. Fods. Kbh., 2 [30], 1914: 31. 



38. Bull. Mus. comp. Zool. Harv., 68, 1927: 246; Canad. Atlant. Fauna, 12*^, 1934; 29. 



39. Goode and Bean, Bull. Essex Inst., 11, 1879: 28. 



40. Goode and Bean, Smithson. Contr. Knowl., 31, 1895: pi. 9, fig. 30; also, Mem. Harv. Mus. comp. Zool., 22, 1896: 

 pi. 9, fig. 30. 



