SHALLOW-WATER STARFISHES 129 



similar. The lower marginal spines form a double row, two 

 divergent spines usually on each plate; these spines are distinctly 

 larger and longer than the dorsals, mostly compressed and somewhat 

 clavate at the tip, and usually bent outward and upward. A single 

 row of synactinal spines of similar size and shape usually occurs on 

 the proximal part of the rays. Adambulacral spines are nearly as 

 long as the actinals and about half as thick, terete, obtuse. On the 

 basal half of the rays they stand two on a plate, forming two 

 divergent rows ; distally they are irregularly alternated, one and two ; 

 those near the mouth are longer. The tip of the jaw bears four 

 divergent spines, the two central stouter but not longer than the 

 adambulacrals, the other two much smaller and about half as long. 



Major pedicellariae of very small size occur singly on many of the 

 adambulacral spines; these are short-ovate or triangular-ovate with 

 acute tips. They are smaller, shorter, and more triangular than 

 those of L. hexactis. Smaller ones also occur on the inner edges of 

 the grooves. Major pedicellariae of very small size occur singly or 

 in small clusters on most of the dorsal and lateral spines, and in 

 somewhat larger groups on the ventral ones. They also occur singly, 

 between the spines, on the back. 



Dr. R, Rathbun has furnished the photographs of the original 

 type of this species, which is still in the U. S, National Museum, 

 (PI. XXV, figs. 5. 6.) 



It agrees very well with several specimens in the Museum of Yale 

 University, from the same locality. Stimpson's description is as 

 follows : 



" Rays six, rather slender and much tapering. Proportion of the 

 diameters, i : 3.5. This species has a general resemblance to 

 A. hexactis in shape, etc., but differs in the character of its spines, 

 particularly the very numerous dorsals, which are uniform in size, 

 and shorter and more crowded, giving to the back in a much greater 

 degree that general evenness of surface which is characteristic of the 

 Stichasters and Cribrellce {Henrici<e'\. These spines are deeply stri- 

 ated or radiated on their flattened heads, each showing eight or nine 

 ridges. On the side of the ray there are two or three rows of longer 

 spines, also striated. The ambulacral spines are for the most part ar- 

 ranged alternately one and two to each plate, but there are two to 

 each plate near the disc. There are minor pedicellariae about all the 

 spines, as in the preceding species [A. hexactis], but they are much 

 less numerous. We can discover no major pedicellariae excepting an 

 occasional small pointed one in the ambulacral furrows. They would 

 zo 



