SOME WEST INDIAN ECHINOIDS. 25 



In the list quoted from the Blalce Echini on pages 23 and 24 it will be observed 

 that the authors of several of the species differ from those used in this work. This 

 is due to the different nomenclatorial principles adopted by Mr. Agassiz and the 

 present writer. Mr. Agassiz holds the not uncommon view "that the author who 

 removes a previously known species to another genus than that to which it was 

 referred by its original describer should put his own name after the species, while 

 the present author, in accordance with the international rules, holds that the name 

 of the first describer of the species should always be kept, but put in a parenthesis, 

 when the species is removed to another genus. Thus, for instance, Spatangus 

 atropos Lamarck for Mr. Agassiz becomes Moira atropos A. Agassiz, while according 

 to the international rules it must be Moira atropos (Lamarck) ; Spatangus pectoralis 

 Lamarck becomes Mctalia pectoralis A. Agassiz, instead of Metalia pectoralis 

 (Lamarck) ; etc. Quite apart from the fact that it is contrary to the rules, this 

 practice of omitting the name of the original author tends to involve the history of 

 the species in more or less obscurity. In case it seems desirable also to add the 

 name of the author of the new combination, it may well be added after the name 

 of the author of the species, as, for instance, Metalia pectoralis (Lamarck) A. 

 Agassiz. By this latter course one is doing justice to both parties. 



While the list in the Blake Echini (excluding the species not found in North 

 America or in the West Indies, as it is done here) numbers 76 species, the revised 

 list numbers 82 species, and probably the number will be somewhat further 

 augmented when all the species have been carefully reexamined. The more 

 important differences between the two lists depend on the removing of such familiar 

 species as Cidaris cidaris (Dorocidaris papillata), Phormosoma placenta, "Astlieno- 

 soma" hystrix («), Echinus acutus, Ech. norvegicus, EcUnocyamus pusillus, Pour- 

 talesia jeffreysi, Spatangus purpureus and Brissopsis lyrifera. The elimination of 

 these European species from the American fauna makes the difference between the 

 European and the North American Echinoid fauna? very pronounced. On the 

 other hand, the presence in both regions of tlie arctic circumpolar Strongylocen- 

 trotus drobacUensis, the almost cosmopolitan Echinocardium cordatum, of such widely 

 distributed deep-sea species as Echinus elegans, E. alexandri, E. affinis, Arxosoma 

 fenestratum, and others, can not prove any near relationship of the two faunas. A 

 different matter is the occurrence of several West Indian littoral Echinoids in the 

 North African region (for instance, Diadema antiUarum, Ecldnonutra lucunter, 

 etc.). These may perhaps be taken to indicate a former land connection (the 

 Archhelenis-Theory) ; but there is always a possibility of their having been trans- 

 ferred as larvffi from the one region to the other. Here, however, a considerable 

 work remains yet to be done. The question whether these species supposed to 

 occur on both sides of the Atlantic are really identical must be carefully remvesti- 

 c^ated In the Report on the Echinoidea of the German South-Polar Expedition, it 

 was proved that the Eucidaris trihuloides from the Cape Xerde Islaiuls differs 

 considerably from that from the West Indies, forming at least a separate variety. 

 This may well be the case with other of these species. Further, it remains to be 

 proved whetlier those species really have pelagic larva?. Of this we know almost 

 nothing, as, in general, we know nothing of the larval development of the tropical 

 echinoderms. What ample fields of most promising research here remain to be 

 opened up! 



