372 Verrill, Notes on Rachata. 



OPHIUROIDEA. 



Ophiactis virescens Lutken. 



Ophiactis virescens Lyinan, Catal., p. 113 ; Verrill, Traus. Coiid. Acad., i, p. 265. 



A few specimens of this species were found adhering among tlie 

 laminated scales of the pearl-oyster {Margaritopliorafi'inbriata). 



ASTERIOIDEA. 



Linckia unifascialis Grray (rar. UfasciaUs), Verrill, op. cit., p. 286. 



Dr. Gray considered this form a distinct species, but the specimens 

 that I have hitherto seen do not appear to warrant their separation 

 from the ordinary X. unifascialis, unkss as a variety. Yet it may 

 eventually prove to be distinct when more and better specimens can 

 be examined. The only diiference observed between them, is the 

 division of the lateral band of pores into two bands toward the base 

 of the rays, in the variety, while it is simple in the normal form. 



This variety appears to be common at Cape St. Lucas and in the 

 Gulf of California, while at Panama it is very rare. 



Occurs from the Gulf of California to Zorritos, Peru. 



Nidorellia armata Gray. 



Fentaceivs {Nidorellia) armatus Gray, Ann. and Mag. N. H.. vol. vi, p. 276, 1840 



Synopsis Starfishes in the Britisli Museum, p. 7, pi. 14, 1866. 

 Oreaster armatus Muller and Tr., Syst. Ast., p. 52, 1842. 

 Goniodiscus conifer Mobius, N'eue Seesterne des Hamburg und Kieler Mus., p. 10, 



Tab. iii, fig. 6. 6, 1859. 

 Goniodiscus armatus Llitlven, Videnslf. Meddel., 1859, p. 75. 

 Nidorellia armata Verrill, Trans. Conn. Acad., vol. i, p. 280. 

 Goniodiscus stella Verrill, op. cit, p. 284, (young), {non Mobius). 



Additional specimens prove that our Goniodiscus stella is merely the 

 young of this species, while in the flat, spineless con<lition. The 

 ch,aracters of tlie young show the close affinity that this genus has 

 with Goniodiscus. 



There is but one specimen from La Paz. Its i-ange is from Guaya- 

 mas to Zori-itos, Peru, 



AMPHIASTER, gen. nov. 



Disk moderately developed, flat above and below, with five broad, 

 triangular rays, and two well developed series of marginal ])lates. 

 Skeleton of the upper eide formed by regular, polygonal, spine bear- 

 ing, tessellated j)lates, with jiores betAveen them ; on the lower side 

 composed of smaller granulated plates, each bearing a t>d)ercle. 

 Marginal plates granulated around the margin, smooth at center, or 



