298 Prof. Agassiz on the Echinodirmata. 



established subsequently to those of Miller among the Cri~ 

 noidea, and which are very numerous, would appear especially 

 to call for revision. M. Alcide d'Orbigny has just under- 

 taken this difficult task, in publishing his ' Histoire naturelle 

 des Crinoides vivans et fossiles,' a work which is based upon 

 the critical examination of a very extensive collection of spe- 

 cimens. It appears to me that the great merit of this mono- 

 graph consists in the systematic arrangement of the genera, 

 which are here distributed into natural families, whilst before 

 we had them disposed without any method, but just as some 

 might happen to follow upon others {pele-mele a la suite les 

 uns des autres). Three parts of this interesting work have 

 already appeared, which contain descriptions of the genera 

 Guettardicrinus, Apiocrinus, and Millericrinus, of the family 

 Apiocrinoidece. It is only to be regretted that M. d'Orbigny 

 was not aware of the labours of M. Ch. Konig, who, in his 

 ' Icones sectiles,' had long since established many genera, of 

 which his Ceriocrinus, Pomotocrinus, and Symphytocrimis 

 appear to me synonymous with those proposed by M. d'Or- 

 bigny. M. L. de Buch has also published, in the Bulletins 

 of the Berlin Academy, a critical investigation of the Sphre- 

 ronites, a group of Crinoidece but little known, and whose 

 structure had escaped the observation of his predecessors. 

 This memoir is accompanied with beautiful figures. Pander 

 has also given, in his 'Beytrage zur Geognosie des Russischen 

 Reichs,' some information upon these fossils, accompanied 

 with figures. Count Munster, in a special memoir upon the 

 fossil Crinoidea, inserted in the '^Acta nova Academ. Ccesar. 

 Leop. Carol. Naturse Curiosorum,' t. xix.&c, has made known 

 a new genus under the name Gasterocoma, and has given ex- 

 cellent figures and admirable descriptions of a large number 

 of species which had not been published in his great work on 

 the fossils of Germany, In his ' Beytrage zur Petrefacten- 

 kunde,' Count Munster has also described many new Cri- 

 noidece of the transition period, among which are three new 

 genera very remarkable for the disposition of the parts of the 

 cup {calice), which, deviating from the quinary type so general 

 in this group of animals, present numbers not found in the 

 class Echinodermata. He calls these genera Diocrinus, Tria- 

 crimis, and Asterocrhms. Count Munster has moreover, in 

 the same work, established his genus Coiaaturella, and de- 

 scribed many new species belonging to known genera. M. 

 Herm. de Meyer has also established two new genera of Cn- 

 noidea in the ' Museum Senkenbergianum' for 1837, under 

 the names Isocrinus and Chelocrmus. M. Bronn has descrilsed 

 the genus Ctenocrinus in the ' Jahrbuch fiir Mineral, u. Petref.' 



