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ECHINOIDEA. II. 



Dorocidaris papillata 



— nuda 



Porocidaris purpurata 

 Phorraosoma placenta 

 Hygrosoma Petersi 

 Sperosoma Grimaldi 

 Dermatodiadema antillarum 

 Salenia hastigera 

 Trisrouocidaris albida 



Genocidaris maculata 

 Echinus atlanticus 



— Alexandri 



— af finis 

 Echinocyatnus pusillus 



— grandiporus 



— macrostomus 

 Calymue relicta 

 Cystechinus clypeatus 



presence of these species and the absence of several remarkable American forms then really seems 

 to mark this part of the Atlantic deep-sea as a separate region, distinct from the American deep-sea 

 region. It is also worth noticing that the Phormosoma placenta of this region appears to be somewhat 

 different from the American form (the Var. Sigsbei). 



The West African Atlantic deep-sea region comprises the tract from the Azores to about 

 St. Helena. With the exception of the sea off the Azores it is very imperfectly known, and the whole 

 «region» will perhaps prove to be untenable, though it now appears to have several species peculiar 

 to it. — The following species are known from this region: 



Aceste bellidifera 

 Palasotropus Hirondellei 

 Peripatagus ductus 

 Homolampas fragilis 

 Hemiaster expergitus 

 Spatangus purpureus 



— Raschi 



Brissus Damesi 

 Brissopsis atlautica(?) 



Of these the following species are known from this region only: Dorocidaris nuda (also littoral), 

 Echinus atlanticus, Echinocyamus macrostomus, Calymnc relicta, Cystechinus clypeatus, Palccotropus Hi- 

 rondellei and Peripatagus ductus. Probably, however, several of these species will prove to have a 

 considerably wider geographical range, and this region upon the whole is very problematic; especially 

 it might be more natural to include the Sea off the Azores in the European atlantic region. 



The East American Atlantic deep-sea region comprises the whole western half of the At- 

 lantic, from the Davis Strait to at least off La Plata, and perhaps even farther southwards. Also the 

 Caribbean Sea and the Mexican Gulf belong to this region. It is, of course, not sharply limited from 

 the East American littoral region, several species ranging from the littoral to the abyssal zone. 



No less than 74 species are known to occur in this region, which is thus by far the richest of 

 all the Atlantic regions. These species are: 



Dorocidaris papillata Hygrosoma Petersi 



Tromikosoma Koehleri 

 Aspidodiadema Jacobyi 

 — tonsum 



Dermatodiadema antillarum 

 Diadema antillarum 

 Hemipedina cubeusis 



— abyssicola 

 Blakei 



— micans 

 Cidaris affiuis 



— tribuloides 

 Tretocidaris Bartletti 

 Stereocidaris ingolfiaua Arbacia punctulata 

 Histocidaris Sharreri Podocidaris scutata 



Phormosoma placenta sculpta 



var. Sigsbei Coelopleurus floridanus 



Calveria hystrix Salenia goesiana 



Arseosoma fenestratum — Pattersoni 



Belli — varispina 



Salenia hastigera 

 Trigonocidaris albida 

 Genocidaris maculata 

 Echinus elegans 



gracilis 

 — Alexandri 



affiuis 



Strongyloceutrotus drobachieusis 

 Psammechiuus variegatus 

 Tripneustes esculentus 

 Echinometra lucuuter 

 Pygastrides relictus 

 Echinocyamus grandiporus 

 Clypeaster latissimus 



