300 Prof. Agassiz on the Echinodermata. 



as it were the precursors of the Comahda, the Asteriee, and the 

 Echinites, the forms of which they have in some instances 

 ah'eady appropriated. In this particular the most remarkable 

 of all the genera is that which I shall describe under the name 

 Echinocrinus, and which presents the perfectly spheroidal 

 shape of the Sea-urchins, with the narrow ambiUacra and 

 long prickly spines of certain Cidarites. The analogy with 

 these last is so striking, that detached fragments of this ge- 

 nus (which is only found in the coal-measures and transition 

 formations) have already actually been described as fragments 

 of Cidarites. Such for instance, among others, are the Cida- 

 ris Urd of Fleming, the Cidarites Nerei, Protei and ji^iscus 

 of Count Munster, and some other unpublished species. 



But little is known at present of the fossil Asterice and 

 OpJmira', a very small number only have been described, 

 amongst which, as new species, I shall mention those which 

 Mr. Williamson has published in Loudon's ' Magazine of Na- 

 tural History ' for 1836, and those from the collections of the 

 Earl of Enniskillen and Sir Philip Egerton, described by Mr. 

 Broderip in the fifth volume of the ' Transactions of the Geo- 

 logical Society of London,' without enumerating those which 

 have been published by Count Munster, M. Goldfuss, M. Des 

 Moulins and M. Agassiz. Their number however is very con- 

 siderable, and I am glad to announce a work by Mr. Dixon 

 which is to embrace all the British species. 



M. Frederic Dubois of Montpereux, in the Atlas of his 

 travels in the Crimea, &c., has commenced the publication of 

 the magnificent collection of fossils brought by him from those 

 countries by the issue of a large plate of highly interesting 

 Echinites. In the fourth volume of the second series of the 

 ' Memoirs of the Academy of Sciences of Turin,' De Sis- 

 monda has published a complete monograph of the fossil 

 Echinites of Piedmont, in Vvhich he describes a new genus un- 

 der the name Auaster, and a large number of new species ac- 

 companied with good figures. M. Grateloup has likewise pub- 

 lished a special memoir upon the fossil Sea-urchins which 

 occur in the calcareous formations in the environs of Dax 

 (Actes dc la Soc. Lin. de Bordeaux, tom. viii.). M. Leymerie 

 has described many interesting species of the genus Diadema 

 in the third vol. of the ' Geol. Trans, of France.' In the same 

 work, vol. ii., M. Dujardin has also described a new Sea- 

 m-chin, from the chalk. M. de France has given, in the 

 ' Dictionary of Natural Sciences' of Le^-rault, numerous ar- 

 ticles on the various genera of fossil Echinodermata, Avhich 

 make us acquainted with the condition of the science upon this 



