CLYPEASTER LEPT( )STRA< % )X. 4 1 



Primary spines smooth and pointed I PL 122, fig. .9), some of the marginal, 

 actinal ones nearly 3 mm. long. Miliary Bpines usually club shaped (PI. 122, 

 fig. 8), but many are not evidently so. Podicellariae only fairly common and 

 not particularly characteristic. Triphyllous (PI. 123, fig. 18), very small with 

 valves only .06 mm. long. Ophicephalous (PI. 123, fig. 17) with heads .25-. 30 

 mm. long and rather slender valves. Tridentate (PI. 123, fig. 20) with straight 

 valves, more or less in contact, and ranging from .10 to .60 mm. in length; the 

 larger ones (PI. 123, fig. 19) have the blade expanded rather abruptly near tip 

 and the margin serrate ; there is often a more or less imperfect loop on the base 

 of these valves. 



In color the specimens (in alcohol) vary from bright yellow or reddish 

 yellow to dirty purplish white; in dry specimens the colors are duller. The 

 yellow specimens have a large number of rather indistinct, dusky blotches on 

 the aboral surface; these are arranged in pairs, four pairs in each ambulacrum 

 and interambulacrum, and form four concentric circles around the petals, parallel 

 to the ambitus. In all the specimens there is more or less contrast in color 

 between the ambulacra and interambulacra on the oral surface. The colors 

 in life are not essentially different. 



The holotype is from Station 4046. 



When young specimens of virescens of the same length as the type of 

 leptostracon are compared with it, the differences in the form of the petals and 

 especially in the form of the test are very marked. The difference in color is 

 also marked. There is no doubt that the two species are perfectly distinct. 

 The series of leptostracon at hand is a very complete one, the specimens ranging 

 from 5.5 mm. in length up to the type, which is seven times as large. In speci- 

 mens under 15 mm. in length the aboral side of the test has numerous deep, 

 irregular pits in the surface; in the smallest specimen these occur everywhere 

 except close to the madreporite, but as the petaloid area grows, the pits are 

 confined more and more to the marginal part of the test and they finally disap- 

 pear altogether. In the youngest specimen, there are but three or four pore- 

 pairs in each petal and the resemblance to Echinocyamus is marked but there are 

 at least ten madreporic pores, instead of the one, characteristic of that genus. 



The Albatross took leptostracon at the following places : — 



Station 3823. Off Lae-o Ka Laau Light, Molokai, Hawaiian Islands. 

 Bott. temp. 69°. 78-222 fms. Fne. s., p. 



Station 3987. Off Hanamaulu, Kauai, H. I. Bott. temp. 73°. 50-55 fms. 

 Crs. co. s., co. frgs. 



