444 
ECHINODEKMATA. 
in characters, the oral almost uniformly covered with large areolar depres- 
sions surrounding spine-tubercles. P. placenta^ sp. n., id. 1. c., off the Butt of the 
Lews. 
Calveria, g. n., id. 1. c. Ambulacral and interambulacral plates form large 
expansions towards the middle line of the area, while their outer portions are 
narrow and strap-shaped, leaving large fenestras filled up with membrane 
between them. Dorsal and ventral surfaces not differing marhcdly. C. hys- 
trixy off the Butt of the Lews, and fenestrattty coast of Portugal, south and 
west of Ireland, deep water, id. 1. c., spp, nn. 
[Phormosoma is not recognized, and the two species of Calveria are not 
distinguished, by Agassiz (Rev. pp. 272-273, pi. 2c), who unites Caheria witli 
Asthemosoma, Q rube, and the Echinothuriince witli the Diadematince ; but 
Wyville Thomson is apparently right in separating them as distinct families.] 
Diadematinae. 
Diadema setosum, Gr. {=^antillarumy savigniiy &c.), Agassiz, Rev. pp. 274- 
276, pi. 
ArbaciindB. 
Troschel (24 ; and SB. Ver. Rheinl. 1872, p. 159) gives the following 
synopsis of the species of Echinocidaris {Arhacia), subdividing it into two 
genera : — 
1. Echinocidaris. None of the ocular plates reach to the periproct : a 
single transverse series of tubercles on the plates of the interambu- 
lacral areee. 
а. A Halted star round the periproct {AgariteSy Ag.). E. punc- 
tidatUy stellatay dufremiiy locidatUy and alternansy sp. n. 
б. No naked star round the periproct {Echinocidaris^. E, pus- 
tulosay ccquituhcrculatay grandinosay and atistralisy sp. n. 
2. Pggotnmay g. n., Trosch. Some of the ocular plates reach the peri- 
proct j beside the principal series of tubercles, mostly small secondary 
tubercles on the plates of the interambulacra. 
a. A nalted star round the periproct. P. spatidigei'um. 
h. TetrapyguSy Ag. No naked star round the periproct. 
P. nigrum. 
In the Echinocidaridee (regarded also by Troschel as a distinct family) a sphee- 
ridium is placed close to the peristome in a small excavation in each ambula- 
crum {Temnotrema = Temnopleurus japonicuSy young \^cf. Agassiz, Rev. 
p. 166]j Purasa/cw7a=^cAfwomc^ra, sp., young (?)). In the detailed paper 
(24) the historical part is treated very fully. 
Arhacia punctulatay Lamk. (^=^davisi)y Agassiz, 1. c. pp. 263-266, pi. j Ccelo- 
pleurus JloridanuSy id. 1. c, pp. 267-269, pi. 2c j Podocidaris scidptUy id. 1. c. 
pp. 269-271, pi. 4. 
Echinometr'wue. 
Strongylocentrotus droebackiensisy Mull. ( Toxopneustes cldoi'ocentrotus and gra- 
mdatuSy &c.), Agassiz, l.c. 276-281, pi. j S. armigei'y id. (1) Bull. (4), Australia. 
Toxopn&ustespalliduSyBTg. n.y^CiVs (19, pp. 25-27), Norway, 30-40 fath. j T.pictuSy 
