446 
ECHINODERMATA. 
Ananchytince , 
PouHalesia 7niranda, Agassiz, I o. pp. 344-347, pi. 18. W. Thomson (23) 
distinguishes two spp. nn., P. jeffi'eysi, north of Shetland, 640 fath., and^jA^/^/e, 
Rockall Channel. According to him, Pourtalesia must be an aberrant form 
in whatever group it may be placed j the apical disk is truly decomposed as 
in the Dymsteridce. • 
Homolainpas fragilisy Agassiz, h c. pp, 347 & 348, pi. 17. 
Spatangina. 
Echinocm'dium cordatum, Penn, (kurtzi, Qir.), E. Jlavescensy Miill. {ovatum), 
pennati/idmnf Norm. {Icevigaster, Ag.) : id. 1. c. pp. 349-352, pis. 19 & 20. 
Agassizia excentrica, Ag. : id. 1. c. pp. 363 & 354, pi. 
Bt'issopsis lyrife7'a, Forb. : id. 1. c. pp. 354-366, pis. 19 & 21. 
Brissus unicolor j Kl. (columharis &c.) : id. 1. c. pp. 366-358, pi. 22. 
Meortia ventrioosa, Link. (=■ Schizaster cubmsis, D’Orb.), id. 1. c. pp. 358 & 
359, pis. 20 & 22. 
MeUdia (Plagionotus) pectoralis, Lmk. : id. 1. c. pp. 360-363, pi. 21. M. stei'- 
nalis, figured by v. Martens (0), pi. 1. fig. 1. 
Schizaster fragiliSf D. & K., Agassiz, 1. c. pp. 363 & 304, pi. 21. 
Afoira atropos, Innk., id. 1. c. pp. 366 & 360, pi. 23 j M. styyia, Ltk. MS., 
id. Bull. 4, Red Sea, Zanzibar. 
Bhynobrissus pyramidalis, Ag., id. ibid., China Sea. 
Lovenia coi'diformis (Ltk. MS.), id. ibid., Guyamas, California. 
Spatangus luetkeni, id. ibid., China Sea ; S. raschi, Lov., abundant in 
gatherings from Fsero to Gibraltar (150-300 fath.), W. Thomson (23). 
Hemiaster experyiUis, sp. n., from the Josephina bank (lat. 38° 7' N., 
long. 9° 18' W., 650 fath.), mentioned, not described, by Lov^n (14, p. 7). 
Palceotropus josephince, g. & sp. nn., Azores, 200-300 fath., mentioned and 
shortly characterized as an aberrant typo of this group, with labrum and 
infra-anul fasciola, two genital pores, ambulacra simple, not petaloid, the 
anterior not impressed nor in any other way different from the other j test 
oval, regularly vaulted. 11'7 mm. long, 9T mm. broad. Id. 1. c. p. 21. 
Lov^n’s elaborate investigations of the structure and composition of the 
test of the Echinidce (14) are incapable of satisfactory abstraction, but have 
been transferred to several widely circulated periodicals. One of the most 
important results is the author’s demonstration, chiefly through the com- 
parative study of Salenia and Alai'supites, that the apical (“genital ”) plates 
of the Echinidce correspond to the ^‘basalia^^ of the CrinoidcB, the ocular 
plates of the former to the radialia of the latter, the central plate of Alarsu- 
pites and Salenia representing the single primary anal plate of the young 
Sea-urchin ! 
Aqassiz, in his “ Revision,’' discusses the geographical distribution of the 
littoral species of Echini, acknowledging four “realms” — the American, 
Pacific, Atlantic (Circumpolar), and Australian (Antarctic) — and eighteen 
districts, or rather geographical categories, encroaching upon each other, and 
comprising each a greater or less assemblage of species, agreeing more or 
less in range, viz. the North Pacific, Boreal American, Californian, Pana- 
mic, Peruvian, Patagonian, Tropical Atlantic, North Atlantic, Lusitanian, 
