66 Memoir Sears Foiindatio?i for Marine Research 



of its genus known from the eastern side of tlie Atlantic by the characters summarized 

 in the preceding Key. Among the species of the west coast of America, it differs sharply 

 from R. flaniceps (Garman) 1880 in having two well developed folds on the posterior 

 margin of each spiracle;*^ from R. glaucostigmus Jordan and Gilbert 1883 and from R. 

 leucorhynchus Gunther 1866 in the fact that its rostral ridges are closely approximated 

 along their anterior third to half. In this respect, R. lentiginosus more closely resembles 

 R. productus Girard 1855, the common Guitarfish of southern California. But there is 

 no likelihood of confusing the two, for the rostral cartilage is considerably narrower 

 toward its tip in R. productus (maximum breadth only about as great as distance be- 

 tween inner ends of nostrils), the first dorsal originates considerably closer to the 

 pelvics,^^ and the tip of the snout lacks the large tubercles that are characteristic of 

 R. lentiginosus. 



Remarks. All specimens of R. lentiginosus reported thus far from Florida and from 

 northward on the east coast of the United States have shown the spotted pattern, as 

 does one in our Study Material from Yucatan. On the other hand, all those from 

 Texas that we have seen are plain-colored, except for one with a few pale dots. It may 

 finally prove that the plain-colored and the spotted forms deserve recognition in nomen- 

 clature, whether as color varieties or possibly as subspecies. But we think it premature 

 to burden ichthyological literature with an additional name before it is known whether 

 the ranges of the two forms are discontinuous, or whether they meet and perhaps inter- 

 grade along the coast of Louisiana, whence one or the other of them, or both, are to 

 be expected though not yet actually reported. 



Size. This Guitarfish is said to grow to a length of "several feet,"^^ but the largest 

 size which we find actually recorded (two females) is 30 inches. Males of 1 9—20 inches 

 already have the claspers well developed (Fig. 14 C). 



Developmental Stages. As noted above, the characteristic color pattern may be 

 developed before birth. A gravid female has been recorded as containing six young. 



Habits. In Florida waters, the only region where more than occasional specimens 

 of R. lentiginosus have been taken, they are often encountered in shallow water around 

 the Florida Keys and along beaches. They have even been observed at Palm Beach, 

 Florida, moving along at low tide with "dorsals and caudals clear of the water, and 

 every few minutes they would poke their snouts up onto the little foot-high shelf that 

 was just wet by the small advancing and receding billows" while feeding.^* But they 

 are also reported as common off Florida in depths as great as 5—10 fathoms.^* They 

 may produce young anywhere within their geographic range, for a female with well 

 developed embryos has been taken as far north as Charleston, South Carolina. Nothing 

 is known of their habits beyond what applies to the genus as a whole, nor of their 

 diet, though it is probable that when they are searching along the intertidal zone on 



51. One spiracular fold only in R. planiceps, two in all other eastern Pacific members of the genus. 



52. Origin of first dorsal is posterior to tips of pelvics by a distance only about half as great as width of mouth or a 

 little more than half as great as length of base of first dorsal in R. productus, but by a distance about as great as 

 width of mouth or about as great as extreme length of first dorsal from origin to rear corner in R. lentiginosus. 



53. Henshall, Bull. U.S. Fish Comm., 14, 1895: 210. 54. Barbour, Copeia, 85, 1920: 71. 



