ECHINOIDEA. II. 



185 



Of these species the following are known from this region alone: Dorocidaris nuda, Rotula 

 Augusti, Ritmphii, Echinolampas Hellei (the Ech. Blanchardi Cotteau is probably only a synonym of 

 this species), Schizastcr Edwardsi, Rhabdobrissus Jiillieni and Metalia africana; whilst Tretocidaris spi- 

 nosa is known only from St. Helena. 



From the Mediterranean region have probably immigrated: Arbacia pustulosa, Par echinus micro- 

 tub ercutattis, Echinus melo and Sphcercchinus granularis, from the East American region: Cidaris tri- 

 buloides, Diadema antillarum, Tripneustes esculentus, Echinometra lucunter, Clypeaster subdepressus 

 and Mcoma ventricosa. The two species Genocidaris maculata and Brissus ^micolor, as stated above, 

 occur; both in the Mediterranean and East American region. It is worth noticing that the species 

 Cidaris tribuloides, Tripneustes esculentus, Echinometra lucunter, Clypeaster subdepressus and Meoma 

 ventricosa are not known from the Mediterranean region. Judging from the currents they (viz. the 

 larvse) must have passed through the latter region; it is then probably the temperature which is not 

 high enough here to suit them. 



The East American littoral region comprises the whole, very extensive tract from the mouth 

 of La Plata in the South to Cape Hatteras in the North. Certainly many of the species of this region 

 do not proceed so far towards North or South, but it is scarcely possible to distinguish more than 

 one region here. Its centre is the West-Indies; from here the species extend more or less in both 

 directions, the North American and Brazilian Coast thus having upon the whole a considerably poorer 

 Echinoid-Fauna than the West Indies, without species peculiar to them (except Paracentrotus Gaimardi 

 which is hitherto known only from the Coast of Brazil). 



This region, together with the East American deep-sea region, is by far the richest of all the 

 Atlantic regions and among the richest of the world. No less than 48 species are known from the 

 East American littoral region against 24 species from the Mediterranean, 23 from the West African 

 tropical, and 20 from the European boreal region. The following species are known from the East 

 American littoral region: 



Dororidaris papillata 



abyssicola 

 Cidaris affinis 



tribuloides 



Tretocidaris Bartletti 

 Aspidodiadema Jacobyi 

 Diadema antillarum 

 Arbacia punctulata 



pustulosa 



Coelopleurus floridanus 

 Salenia Pattersoni 

 Trigonocidaris albida 



Genocidaris maculata 

 Echinus gracilis 

 Paracentrotus Gaimardi 

 Psammechinus variegatus 

 Tripneustes esculentus 

 Echinometra lucunter 



viridis 



Clypeaster latissimus 

 Ravenellii 

 snbdepressus 

 Echiuanthus rosaceus 

 Mellita sexforis 



Mellita testudinata 

 Encope marginata 

 Michelini 

 Echinoneus semilunaris 

 Echinolampas depressa 

 Conolatnpas Sigsbei 

 Rhyncopygus caribbsearum 

 Palseotropus Josephinse 

 Palseopneustes cristatus 



hystrix 



Linopneustes longispinus 

 Palaeobrissus Hilgardi 



semilunaris As long, however, as we know almost nothing of the littoral fauna of St. Helena and the West Coast of Africa 

 South of Congo, we cannot deny the possibility of the occurrence of these species at Ascension; the streams of the Southern 

 Atlantic at least would easily account for their occurrence there, if they were only found off South Africa. But only Cidaris 

 metularia has been recorded from there, and only from older collections (Rev. of Ech.). 



The Ingolf-Rxpedition. IV. 2. 24 



