78 ASTEROIDEA. 
Distribution. Northern parts of Atlantic, on both sides; White 
Sea. To 150 fms. 
a. Coast of Northumberland. R. Howse, Esq. 
b. Coast of Northumberland. 
ce. North of England. Dr. G. Johnston. 
d. North of England. Dr. G. Johnston. 
(4-rayed form.) 
e. St. Abb’s Head, Berwickshire. Prof. E. Forbes. 
fg. St. Andrews. Prof. M‘Intosh. 
h, z. Montrose, July 1889, W. Duncan, Esq. 
Jj. Aberdeen. L. G. Esson, Esq. 
k,l. Coast of Ross-shire. Dr. Sutherland. 
m, n. English coast. Dr. Bowerbank. 
MIMASTERIN-A (see p. 21). 
MIMASTER. 
Mimaster, Sladen, Proc. Roy. Soc. Ed. xi. (1882) p, 702; id. Trans. Roy. 
Soc. Ed. xxx. (1885) p. 579; zd. Chall. Rep. Ast, (1889) p. 381. 
With the characters of the subfamily (see p. 21). 
1. Mimaster tizardi. 
Mimaster tizardi, Sladen, Proc. R. Soc. Edinb. xi. (1882) p. 702 ; id. 
Trans. R. Soe, Edinb. xxx. (1888) p. 580, pl. xxxiv. ; zd. Chall. 
Rep. Ast. (1889) p. 338. 
R= 27. 
A large species, with short triangular rays, swollen disk, thin 
margins formed by the marginal plates alone. Paxille compact and 
subequal. Rather less than forty marginal plates in each series, the 
lower larger than the upper. Adambulacral armature formed of 
delicate spines varying in number and arrangement. Madreporite 
obscure. 
Colour, in spirit, yellowish or light brown. 
a. Faeroe Channel, 555 fms. ‘ Knight Errant’ Exp. (St. 4). 
b, c. Faeroe Channel, 516 fms. ‘ Triton’ Exp. (St. 19). 
d, Faeroe Channel, 555 fms. ‘Triton ’ Exp. (St. 11). 
Not known from any other locality. 
GYMNASTERIID & (see p. 21). 
Key to the Genera of Gymnasteriide. 
A.. No spines on dorsal plates 2. .0...000.s00 1. Porani, p. 79. 
B. Spines or spinelets on dorsal plates. 
a, Superomarginals obscure. 
1, With no broad marginal fringe .. 2. RueGaAsTER, p. 80. 
ii, With a broad marginal fringe .... 3. CHEILASTER, p. 81. 
8. Superomarginals distinct ............ 4, LASIASTER, p. 81. 
