HYPSELASTER ROTUNDUS. 187 



are 4-5 mm. long, but within the fasciole there are a number of primary tuba 



which must have carried much larger spines. 



The pedicellariae are rather few. A single triphyllous was found, with 

 rather narrow leaf-shaped valves about .10 mm. long. There wen- no globi- 

 ferous pedicellariae seen but a number of tridentate occur. These are remark- 

 able for their very slender valves, which measure fully 1.25 mm. in length, 

 but have the base only .30 mm. wide and the slightly expanded tip only .10 mm. 

 The valves are in shape very much like those of Spatangus purpureas as figured 

 by Mortensen (1907, Ingolf Ech., pt. 2, pi. 16, figs. 1 and 9). 



Station 4130. Off Hanamaulu, Kauai, Hawaiian Islands. Bott. temp. 

 46.1°. 283-309 fms. Fne. gy. s. 



Hypselaster limicolus. 



Schizaster (Periaster) limicola A. Agassiz, 1878. Bull. M. C. Z., 5, p. 193. 



This interesting spatangoid was taken in the Gulf of Mexico by the Blake 

 in 118 fms. It is also known from the Albatross collections in the Gulf of 

 Mexico at a slightly greater depth (142 fms.). The record in the Challenger 

 Report of its occurrence in the Arafura Sea has been shown by Mr. Agassiz 

 to be a mistake and Mortensen has further shown that the specimens from 

 the Arafura Sea do not belong to the present genus. On the other hand Bris- 

 sopsis alta Mortensen occurs abundantly at the Blake station in the Gulf 

 of Mexico where limicolus was first taken and as the form of the test is very 

 similar, specimens of the Brissopsis have been identified and distributed as 

 "Periaster limicola" and this has naturally led to confusion. The absence of a 

 subanal fasciole and the presence of only 2 genital pores are sufficient ly evident 

 characters by which to distinguish Hypselaster easily. The pedicellariae of 

 this species have been fully described by Mortensen. 



Hypselaster rotundus. 



Periaster rotundus A. Agassiz and Clark, 1907. Bull. M. C. Z., 61, p. 138. 



Plates 146, figs. 9, 10; 148, figs. 1, 2; 154, figs. 11-14- 



Length 37 mm.; width, anterior to apical system, 35 mm.; height pos- 

 teriorly 31 mm. The general form of the test may be better understood from 

 the figures (PI. 154, figs. 11-14) than from any description. The peripetaloua 



