ECHINODERMATA. 147 
dichotomously and afterwards into many branches, in Astrophyton 
Lixcx. To the last division belongs : 
Sp. Luryale verrucosum LamM., Asterias Caput Meduse L. (in part) Rumputvs, 
Amb. Rariteitkamer Tab. xvi. Cuv. R. Ani., édit. ilus., Zooph. Pl. 3, from 
the Indian Sea; a very similar species is found in the North Seas, and 
distinguished by MUELLER and TROSCHELL as Astrophyton Linckii ; Linox 
de Stell. mar. Tab. 29, fig. 48. These Medusa-heads belong to the most 
singular and beautiful forms of radiate animals. Vid. Forbes Br. Star- 
Jishes, pp. 67--70. 
Ophiura Lam. Arms five, undivided, serving for creeping, scu- 
tate, articulate. Disc plane, with two or four genital fissures in 
each interbrachial area on the ventral side. 
The name Ophiura, from équs, serpent, and oupa, tail, denotes very 
appropriately the form of the arms by which these Sea-stars are 
distinguished, and which are often so long as to exceed five or six 
times (nay in Ophiura longipeda even twenty times) the diameter 
of the disc. 
Sub-genera : Ophiocoma Acass., Ophiolepis, Ophiarachna, Ophia- 
cantha, Ophiomastix, Ophiomyxa, Ophioscolea, Ophiothriz, Ophio- 
enemis, Ophioderma, Muxrut. and Troscu. 
Sp. Ophiura teaturata Lam., Asterias ophiura L. (in part), Ophiolepis ciliata 
MUELL. and Troscn., Linox de Stell. mar. Tab. 11. fig. 4, Encyclop. Pl. 123, 
fig. 2, 3. Forbes British Starf. p. 22, &c. in the Mediterranean, the 
North Sea, &e. 
Phalanx II. Asteriw. Body depressed, angulate or stellate 
the angles being produced, with tentaculiferous furrows below, ex- 
tending as far as the point of the angles. Anus dorsal in most, 
surrounded by a mound of calcareous papillee. 
Asteria Lam. (Most are species from the genus Asterzas L.) 
The Sea-stars. The form is very various, so that in some species 
the entire body seems to consist only of arms, ex. gr. in Ophidiaster, 
in others only of a pentagonal disc. But the arms are never 
sharply separate from the disc as in the Ophiure, but are an 
immediate continuation of it. In most of the species there are five 
rays, however in these sometimes four or six occur as exceptions ; 
six arms as the normal number are found in Asterias gelatinosa, in 
Echinaster eridanella, six or seven in Asteriscus Diesingii, seven to 
nine in the sub-genus Luidia, eight to ten, mostly nine, in Solaster 
endeca, eleven to fourteen, generally twelve, in Solaster papposus, 
twelve or thirteen in Asterias aster, fifteen in Asteriscus rosaceus, 
10—2 
