A Revised Lid of Brllish Echinoidea. 403 



. All these except Echinus melo, Stronfjylocentrotus lividus, 

 and Sphcerechinus granularis are also in the preceding list, 

 so that we may conclude that one great contingent of the 

 British Echinoid fauna is made up of forms extending from 

 JSTorway round to the Mediterranean. 



Some of them have a still more extended distribution, as, for 

 example, Cidaris papillata, which extends across the Atlantic 

 and even to the Philippines ; Echinus acutus, reported from 

 the United States, Ascension, and the Kermadec Islands ; 

 Strongylocentrotus drobachiensis, recorded from Greenland ; 

 and Echinocardiicm peimatifidAim, from the West Indies. 



Another section of this fauna is derived from the deep 

 water of the Atlantic, and would be excluded by those who 

 contend that the British area should be limited by the 

 hundred fathom line. Such forms are — 



Cidaris purpurata. 

 Phormosoma placenta. 



Neolampas rostellata. 

 Spatangus Raschi. 



uranus. Pourtalcsia miranda. 



Asthenosoma hystrix. 



, , feiiestratum. 



Echinus microstoma. 



Jeffreysii. 

 phyale. 



CIDAROIDA. 



Mouth and anus central and opposite, the latter within the 

 dorso-central system ; internal branchite only ; jaws present, 

 perignathic girdle discontinuous ; both ambulacral and inter- 

 ambulacral plates continued beyond the peristome to the true 

 mouth. 



ClDARID^. 



1. Cidaris, Klein. 

 Body spheroidal ; peristome and periproct subequal ; primary 

 tubercles very large and perforated ; spines of various forms. 



Subgenus Dorocidaris, Agassiz. 

 1869. Dorocidaris, Agassiz, Bull. ]\Ius. Comp, ZooL, i., p, 253. 



Ambulacral median area narrow ; primary tubercles without 

 crenulations, surrounded by a deeply-sunk scrobicular area, formed 

 of close granulations ; spines very long, often twice the diameter 

 of the body -, grooved, the ridges often consisting of rows of 

 tubercles ; pores disconnected. 



