328 ALLAN HANXOCK PACIFIC EXPEDITIONS VOL. 8 



wide near the very blunt tip, their lunules are a little longer (about 8 mm) 

 but scarcely wider than the anterior 3. Unpaired lunule nearly 12x3 mm, 

 and almost wholly within the area limited by the posterior petals. Its 

 surrounding spines are relatively long (2-4 mm) flattened, particularly 

 at the somewhat truncated tips, which, however, are not chisel-shaped. 

 Entire upper surface of test densely covered with very low spines each of 

 which is an inverted cone; the bases of these cones form a very smooth 

 secondaiy surface for the upper side of the animal. Only around the 

 lunules and at the very margin of the disk are there really spinelets and 

 these are definitely blunt, though the tips of many are rounded at the 

 corners. Lower surface as usual in the genus, the spines long and slender 

 (4-5 mm) but lying more or less flat against the test, pointing towards the 

 mouth on interambulacra 1 and 4 and towards the margin on inter- 

 ambulacra 2 and 3 ; on interambulacrum 5 they all tend to point towards 

 the lunule, as they do on the five ambulacra. 



No two of the 33 specimens are exactly alike in color, but in general 

 they may be called olive brown lighter towards the center. Many speci- 

 mens are darker than the holotype, appearing to be clove brown or even 

 bone brown. None, however, approach the olive gray (almost deep green) 

 of wetmorei. The marginal spines and the lower surface are definitely 

 brown lacking the olive tint. The cleaned test where bare and dry (but not 

 at all bleached) is a pale olive gray rather markedly in contrast with the 

 normal olive brown of the spine-coat. While this species resembles both 

 perspective and wetmorei in the position of the posterior lunule, it cannot 

 well be referred to either one. It seems best to regard it as a related but 

 distinct species. A specimen, for deposit in the National Museum, was sent 

 to Mr. Austin Clark. He, however, fails to see any essential difference 

 between it and •wetmorei. Further careful study of the material at hand 

 compels me to maintain laevis as a well-marked species. 



Distribution. — All of the specimens of this species are from Station 

 962-39, 1 1 miles northwest of Corinto, Nicaragua, in 1-3 fms on a bottom 

 of sand and dead leaves. 



Type. — AHF no. 51, 32 paratypes. 



Type locality.— Station 962-39, 1 1 miles NW of Corinto, Nicaragua, 

 1-3 fms May 4, 1939. 



Distribution. — Nicaragua. 



Depth.— 1-3 fms. 



Specimens examined. — The type and paratypes, from 1 station. 



