271 



lacral spines cylindrical with bluntly rounded tips, forming (except 

 toward the extremity of the ray) two regular rows, two to each 

 plate, and bearing small chisters of minor pedicellari£e at their outer 

 bases. Ventral and lateral spines in regular rows, but passing imper- 

 ceptibly into the dorsal spines on the high rounded side of the ray ; — 

 four of these rows may be counted, in which the spines are small, 

 slender, shorter, and more pointed than the ambulacral spines, and 

 surrounded at base by thick wreaths of minor pedicellaria?, which 

 wreaths, in alcoholic specimens, touch each other at their bases. The 

 dorsal ossicles, with their interspaces, are mostly transverse in direc- 

 tion on the rays, and anastomose pretty closely, except that there is 

 on each side a series of transverse membranous interspaces much 

 larger than the rest (often one-fifth the width of the ray) and each 

 containing from two to five papula?. The papula? elsewhere stand 

 singly, sometimes two together. The dorsal spines are very numer- 

 ous, minute, no thicker, and much shorter than the latero-ventrals, 

 and are more or less capitate ; — they are somewhat variable in size, 

 and arranged in groups on the ossicles. Among them are considera- 

 ble numbers of minor pedicellarias, which are often half as large as the 

 spines themselves. On the disc the spines are very much crowded, 

 as they also are along the middle of the ray, forming a more or less 

 distinct median series. The spines of the eyelids and extremities of 

 the rays are much stouter than any of the others either above or 

 below. The madreporic plate is large, but not surrounded by any 

 sj^ecial arrangement of protecting spines. The minor pedicellarise in 

 this species are strongly truncated at the extremity. The major 

 pedicellariae are few in number, and situated on the disc below, — 

 small ones at the inner bases of the labial spines, — and two or three 

 very large ones in the angle of the rays ; the latter having stout, 

 almost cylindrical valves, one of which is sometimes notched at the 

 extremity for the reception of the point of the other. A large speci- 

 men, probably of this species, was found, in which some of these large 

 major pedicellariae also occurred on the sides of the rays. 



Diameter, usually two and one-half inches. 



This fine species appears to be allied to A. Mullen, although so 

 different in aspect. 



Dredged in considerable numbers on a muddy bottom in from 

 twenty to thirty fathoms, in the Arctic Ocean, north of Behring's 

 Straits. U. S. North Pacific Expedition. Capt. John Rodgers. 



ASTERIAS ACERVATA (uOV. sp.) 



Rays six, more convex and more tapering than in A. jjolaris. Disc 

 of moderate size. Proportion of the diameters, 1 : 4.5. Ambulacral 

 spines in two rows (two to each plate), rather stout, cylindrical, and 



