438 PROCEEDINGS OF THE NATIONAL MUSEUM vol.89 



peristome, which is nearly as wide as long. Ambulacral plates form 

 five small knobs, which project rather conspicuously over the 

 peristome, more noticeably than in the other species of the genus. 

 Ambulacral furrows of lower surface conspicuous, the intermediate 

 area in each ambulacrum not very broad; in II and IV these areas 

 are about 40 mm. long by 15 mm, wide. 



Primary spines of the dorsal surface less than 1 mm. long, very 

 slender, but conspicuously and rather abruptly capitate, the heads 

 being noticeably larger than in the other species. Surrounding the 

 lunules and around the margins of the test the primaries are 2 to 

 3 mm. long, flattened and blunt, not at all capitate; around the 

 lunules, particularly the unpaired one, they are markedly widened 

 at tip. On the oral surface the spines are 4 mm. long, more or less, 

 very slender, and are nearly horizontal in position; in the anterior 

 interambulacra (2 and 3) they point outward, but in 1 and 4 they 

 point inward, while in 5 they point to the lunule or midline. Pro- 

 longed search over both the holotype and the equally well preserved 

 paratype failed to reveal even a single j^edicellaria. 



Color greenish gray above with the margins of the lunules and 

 of the test appearing more silvery, owing to the translucency of the 

 longer spines; the lower surface is definitely brown, except as modi- 

 fied by the silvery spines 



Locality. — Near Port Limon, Costa Rica, from "high and dry" 

 on the sand beach ; George T. Kenley, collector. 



Holotype.— VS.'^M. No. E. 5655. 



Notes. — Besides the holotype there are two paratypes taken at the 

 same time and place by Mr. Kenley. The larger is 60 mm. long, 

 72 mm. wide, and 6.5 mm. high. The form of the test and general 

 appearance are exactly as in the holotype, except that the color is 

 distinctly brown on both surfaces. Under a lens the large, flat, 

 broad-tipped spines bordering the unpaired lunule show clearly a 

 fundamental green-gray color (as in the holotype) slightly tinted 

 with brown. As this specimen was taken in about 3 feet of water, 

 it is not unlikely that the normal color of lata is brown and the 

 greenish gray of the dorsal surface of the holotype is due to bleach- 

 ing while "high and dry" on the beach. 



The third specimen from Port Limon is a bare and defective test 

 59 by 71 mm. showing no notable peculiarities. 



There are also in the National ISIuseum material two small bare 

 tests, which, in spite of their obvious immaturity, may yet be con- 

 sidered paratypes. The larger is 48 by 58 by 7 mm. and is thus 

 relatively high, while the anterior upward slope of the test is more 

 abrupt than in any other specimen. The smaller is 40 by 44 by 4.5 mm., 

 the length and breadth being more nearly equal than in adults. 



