HYPSELASTER BRACHYPETALUS. 191 



Hypselaster brachypetalus, 1 sp. nov. 

 Plates 148, figs. 8, 4; 154, figs. 1-8. 



Length, 25 mm.; width of test, where widest, near middle, 21 mm.; height 

 of test where highest, near posterior end, 17.5 mm. The form of the test will 

 be most clearly understood from the figures (PI. 154, figs. 1-8). The abactinal 

 part of interambulacrum 5 forms a distinct, though rounded, keel. Peripeta- 

 lous fasciole distinct but narrow and of nearly uniform width; it encloses an 

 area only 14 mm. long and 12 mm. wide. There is no trace of an anal fasciole 

 unless a single, very regular series of minute miliary tubercles is to be so inter- 

 preted; this series is about 3 mm. long and lies 4 mm. below the periproct. 

 The petals are very little sunken. Petal III is about 9 mm. long and scarcely 

 1.5 mm. wide, while petals II and IV are 6.5 long by 2 wide. These latter 

 petals have about thirteen pore-pairs on each side, but in petals I and V, which 

 are only 2 mm. long there are barely half a dozen pore-pairs on each side (PI. 

 148, fig. 8). Genital pores 2, large, completely obscuring the sutures between 

 genitals 1 and 2 on the one hand, and 3 and 4 on the other. Periproct near upper 

 margin of posterior end, oval, narrower above, about 3 mm. high by 2.5 mm. 

 wide, covered by relatively few plates, the two largest occupying the whole of 

 the upper, narrow end. There are no conspicuous tube-feet at posterior end 

 of test. Sternum somewhat projecting, about 12 mm. long by 6 mm. wide pos- 

 teriorly. Labrum (PI. 148, fig. 4) short, markedly T-shaped, not as long as 

 the first ambulacral plates. Peristome much wider than long covered by many 

 small, thin plates; it is scarcely sunken at all and the labium projects but little. 

 Color of test and spines, in the dry specimen, nearly white, with the peripetalous 

 fasciole light brown; the dried spine-muscles give a brown cast to the anterior 

 end of test and the sternum. Primary spines broken or wanting. 



Of pedicellariae, I have found only a couple of tridentate but these proved 

 of no little interest because they so closely resemble those of H. kempi as figured 

 by Koehler (1914. Ech. Indian Mus. Spat., pi. 19, figs. 8-10). The valves 

 are straight, about .33 mm. long, very little compressed and with nearly parallel 

 sides, which are conspicuously serrate. The blade is widest near tip, but it is 

 very little narrower at its base. 



There can be no doubt that this species is nearly allied to the preceding and 

 I greatly regret that no globiferous pedicellariae were found on the specimen, 



1 Bpaxh = short + irkraKov = a petal, in allusion to the very short posterior petals. 



