% BULLETIN 7(1. UNITED STATES NATIONAL MUSEUM 



Very small lanceolate pedicellariae are found on the abactinal surface. Ovate 

 to lanceolate acute, larger ones, as largo as 0.8 mm. long, arc found rather plentifully 

 in the marginal and actinal channels, on the proximal adambulacral spines, oral 

 spines, and along the furrow face of the adambulacrals. 



Crossed pedicellariae, variable in numbers, are distributed as in camtschatica. 

 Tiny are frequently abundant inferomarginally and actinally. The abactinal 

 measure 0.24 to 0.27 mm. 



Madreporic plate inconspicuous, partly overhung by the numerous encircling 



spinelets. 



Anatomical notes.— There is nothing peculiar or unusual about the skeleton of 

 this form. The carinal plates are conspicuous when denuded and are imbricated 

 directly to form an irregular series. They appear to have been originally four 

 Lobed; in adult specimens the contour is irregular. The marginal and actinal plates 

 have a warped 4-lobed contour, the upper or outer lobe being more advanced toward 

 end of ray (transverse axis of plate, oblique). The outer row or actinals nearly 

 reaches the end of ray while the inner attains about the middle, measured on side. 

 The dorsolaterals, smaller than either marginals or carinals, are irregular in contour 

 and without regularity in arrangement. The intervals of the skeleton are smaller 

 than plates on basal half of lay; slightly larger on distal half. 



Variations. — The dorsolateral spinelets become a little more widely spaced while 

 the carinal are aggregated into slight convex differentiated groups. These groups 

 are not as prominent as in typical dispar. L. dispar may be achieved by the reduction 

 in the number of the dorsolateral and superomarginal spinelets. These incipiently 

 "acervate" examples are found at Kodiak Island (Karluk) (pi. 50, fig. 1), Unalaska, 

 Pribilof Islands (St. Paul and St. George). A number of specimens from St. George 

 (pi. 49, fig. 4) exhibit this variation in a marked degree and I have noted them under 

 dispar although they are really perhaps as close to nitida. The spines of the convex 

 carinal groups are closely aggregated. At the base of the ray there are sometimes 

 one or two adradial clusters. Superomarginals, two or three. 



As mentioned above this incipiently clustered condition of the carinal spinelets 

 is shown by a fow specimens from Karluk, Kodiak, which resemble and may perhaps 

 be intermediate with L. hexactis f. siderea, which occurs with them, at low tide. 



Type ofjorma nitida— Gat. No. E149I5, U.S.N.M. 



Type locality. — St. Paul, Pribilof Islands, Bering Sea, rocks at low tide. Col- 

 lected by William Palmer. 



Distribution. Pribilof Islands, Unalaska, and Kodiak (Karluk). 



Forma NESIOTIS, new forma 



Plato 42, Figures 2, 2a; Plate 40, Figure 3 



This differs from forma nitida in having much more delicate spinelets. Typi- 

 cally the carinal spinelets are not any larger or only slightly larger than the other 

 abactinal spinelets and the mouth plates generally have two spines each at the acti- 

 nostomial end. 



The abactinal skeleton is sometimes more open than in nitida, the papular areas 

 forming longiseries of which one above the superomarginal plates and ono on either 

 side of the carinals is evident, while one between these two is likely to be broken up. 



