■\Ji-. J. W. Salter on some new Pahcozoic Star-fishes. 327 



Palasterina, M'Coy (proposed J 831). 



The type of this genus is the Uraster ])riin(pvus of Forbes, but 

 he would have referred it, and with it the whole group, to their 

 true position near Astcriscus [Palinipes) but for an accident. In 

 his enumeration of the fossil Asteriadse*, he quotes the Asterias 

 antiqua of llisiuger, not among the palaeozoic rocks of Gothland, 

 its real locahty, but as from the cretaceous strata of Sweden. 

 Its aspect is so much like that of the Goniasters, frequent in the 

 cretaceous rocks, that the mistake is easily accounted for. It is 

 an excellent species of Palasterina, and appears to differ from 

 the Bi'itish one chiefly in the large size of the disk, and conse- 

 quent pentagonal outline. 



P. antiqua, Hisinger, Leth. Suec. p. 89. t. 26. f. 6. 

 Lac. Mt. Hoburg, Gothland, Sweden ; in Ludlow rocks. 



1. P. primcEva, Forbes, Mem. Geol. Surv. Dec. 1. pi. 1. 

 PI. IX. fig. 2. 



P. brachiis triangularibus acuminatis, disco lato brevioribus ; pagina 

 superior! tuberculata, brevi-spinosa ; ossiculis [adjambulacralibus 

 subquadratis, couvexis, basalibus majoribus. 



The basal, or angle-ossicula are enlarged, three-cornered, and 

 furnished with a pjTamid of spines pointed inwards. The upper 

 surface is roughly tuberculate, and with short tufts of spines. 



Loc. Underbarrow, Westmoreland ; a common species in the 

 Ludlow rocks. Leiutwardine, Shropshire (fig. 2 is from thence). 



Pal/Eocoma, n. g. 



These diiFer widely from Palasterina in appearance, and in the 

 much smaller amount of calcareous matter entering into the 

 composition of their skeleton. Yet the principal characters by 

 which they diiFer are the elongated shape of the narrow ambu- 

 lacral bones and the double row of bordering plates, the outer 

 of which bears the combs of long spines. 



The spines are often so long as to form a complete fringe, and 

 in one species, P. Colvini, the disk is equally spiuiferous. In 

 the curious subgenus Bdellacoma they are short, and intermixed 

 with some larger clavate spines on the upper surfaces. And in 

 the extreme form, Wiopalocoma, which may hereafter have to be 

 separated as a distinct genus, the hair-like spines are all absent, 

 and clavate ones take their place. 



* Mem. Geol. Surv, vol. ii. pt. 2. p. 481. 



