267 



ASTERIAS RUGISPIXA (nov. sp.) 



Rays five, rather broad at the base, flattened above and below, 

 with the sides nearly perpendicular ; latero-inferior angle acute ; 

 ossicles very regular ; disc large. Proportion of the diameters, 1 : 3. 

 Ambulacral furrows broad, with the pores in four rows. Ambulacra! 

 spines in one row, rather large, longer than the ventrals, slightly cla- 

 vate, and granulated toward their bluntly-rounded tips. In the fur- 

 rows, at the bases of the ambulacral spines, there are a few major 

 pedicellariaj twice as long as broad. Ventral spines in two or three 

 rows, and similar in form to the ambulacral spines, but with more 

 flattened and rugose heads. The outer row, on the angle of the ray, 

 is the most distinct. The side of the ray, between this angle and the 

 margin row of dorsal spines, is bare of spines, but has scattered pedi- 

 cellarige of both kinds. The dorsal spines are few in number, and of 

 small but uniform size, being as thick but only half as long as the 

 ventrals. They are regularly capitate, and the heads appear as if 

 corrugated, being sculptured with radiating, tuberculated ridges. 

 With the exception of the marginal ones, which form a regular row 

 (of eighteen spines), the dorsal spines are, for the most part, irregu- 

 larly scattered. Those on the disc generally form a circle or penta- 

 gon. The madreporic plate is made up of very few laminaB, and is 

 situated in the periphery of the pentagon, half way from the centre 

 to the margin of the disc. Papulae crowded, in numerous groups. 

 IVIinor pedicellarias are scattered between the dorsal spines, mostly 

 near the lateral rows. 



In this species the minor pedicellariie (or what we take to be 

 their representatives) are much larger than usual, being at least one- 

 third the size of the major ones. They are also of peculiar though 

 variable shape, often approaching the broadly valvate form seen in 

 the Goniasters, etc. Their valves are usually flattened, rounded, and 

 expanded, much broader than long. Sometimes one valve is much 

 larger than the other, and double forms occur, in which a thick cen- 

 tral valve has two others lapping against it from opposite directions, 

 one on each side. Diameter, two and three-tenths inches. 



Habitat, Orange Harbor, Terra del Fuego. U. S. Exploring Ex- 

 pedition. 



AsTERiAS Troschelii (nov. sp.) 



Eays five, slender, and somewhat pentagonal, regularly tapering to 

 a point ; disc small. Proportion of the diameters, 1 : 7. Ambulacral 

 pores in four regular rows. Ambulacral spines in two or three 

 rows, generally two, but occasionally one, to each plate ; they are 

 sub-cylindrical, and bear clusters of minor pedicellariae at the middle 

 of their outer sides. There are four rows of ventral spines (rarely 

 five, near the base of the ray), which are longer than the ambulac- 



