PTPRASTER. 93 
1, PTERASTER. 
Pteraster, M. Tr. Syst. Ast, (1842) p. 127; Sladen, Chall. Rep. Ast. 
(1889) p. 469, 
A Pterasterid in which the adambulacral plates carry transverse 
combs of spines; the spines are webbed; the supradorsal membrane 
is provided with muscular fibrous bands, which are not arranged in 
a reticular manner, and usually contains spicules. 
1. Pteraster militaris. 
Asterias militaris, O. FF. Miill. Prod. Zool. Dan. (1776) p. 234, 
no. 2828; J. Rathke, in Zool. Dan. iv. (1806) p. 13, pl. 131. 
Asteriscus militaris, M. Tr. Syst. Ast. (1842) p. 44. 
Pteraster militaris, zd. t.c. p. 128; Diib. § Kor. Vet.-Ak. Hadlg. 
1844 (1846) p. 246, pl. vil. figs. 11-13; Steomps. Inv. Grand Manan, 
(1853) p. 15; Kor. § Dan. Faun. litt. Norv. ii. (1856) p. 55, 
pl. viii. figs. 1-8; Lith. Vid. Medd. 1857, p. 43; Sars, Norg. 
Ech. (1861) p. 48, pl. iii. figs. 8, 9, pls. iv., v., vi. figs. 1-13; 
Duj. § Hup. Echin. (1862) p. 434; Moeb. § Biitschli, JB. Comm. 
Kiel, ii. & iii. (1875) p. 147; Perr, Arch. Zool. exp. v. (1876) p. 301 ; 
Kor. § Dan. Norske Nordhavs Asteroidea, (1884) p. 70; Slad. 
Chall. Rep. Ast. (1889) p. 471. 
R=2 7 
Body high, stellate, the sides of adjoining rays forming a slightly 
obtuse angle with one another ; ambulacra moderately wide, bounded 
by a transverse comb of four to six spines; this is on its outer side 
attached to the membrane which connects the marginal spines with 
one another. The paxilliform spines which bear the supradorsal 
membrane end in two or three spinelets. 
R=22°5; r=10°5. Greatest height=13. Breadth of arm at 
base 14 millim. 
Distribution. Both sides of North Atlantic, as far south as Grand 
Manan on the west and coast of Norway on the east. A charac- 
teristic arctic form, and said to increase in size the further north it 
is met with. 10-600 fms. 
a. Faeroe Channel, 530 fms. ‘Triton’ Exp. 
Var. prolata. 
Pteraster militaris, var. prolata, Sladen, Trans. Roy. Soc. Ed. xxxii. 
(1884) p. 153, pl. xxvi. fig. 1; 2%. Chall. Rep. Ast. (1889) 
p. 472. 
Mr. Sladen distinguishes a specimen from the Faeroe Channel 
(608 fms.) in which, “although it accords in the main with the 
diagnostic formula of that species [1. e. ?. militaris}, the majority of 
the characters differ more or less in degree.” ‘The rays are said to 
be longand narrow. R=58 to 60 millim.; r=18 millim. Ihave 
not seen the form, and haye no opinion to offer. 
