104 E. ETHERIDGE, JUtf., Otf ASTKOCEINITES. 



Cystidea of M. von Buch, and the Crinoidea generally," gave the 

 horizon and locality as Carboniferous Limestone, Yorkshire*. The 

 name Astracrinites has been rejected by Dr. H. G. Bronn, on 

 account of its close resemblance to Aster •ocrinites, Minister ; and he 

 has proposed in its place that of Zygocrinus f. Dr. P. Eomer 

 observes that the four-rayed structure of this fossil more properly 

 allies it with the Cystoidea than "with the Blastoidea, ivliieh it other- 

 ivise considerably resembles J. 



Prof, de Koninck and M. le Hon § refer Zygocrinus to the Blas- 

 toidea, and state that the genus differs from Pentremites by the 

 absence of ovarian apertures and the possession of separate openings 

 for the mouth and anus. 



Prof. Morris has altered Austin's name Astracrinites into Astro- 

 crinus\\, and does not recognize Bronn's name Zygocrinus in con- 

 nexion with it. He gives Settle as the locality. 



The late Prof. Pictet provisionally placed Zygocrinus in the Blas- 

 toidea, stating at the same time that its structure indicated a com- 

 plete analogy with that of Codaster [Codonaster~], M'Coy, except that 

 it possesses four pseudambulacra, instead of five as in the latter %. 



The substitution of generic names by various authors for trivial 

 causes has given rise to endless coufusion ; and as I cannot perceive 

 the desirability of adopting Dr. Bronn's substitution of Zygocrinus 

 for Austin's Astrocrinites, I have much pleasure in restoring the 

 latter, notwithstanding its resemblance to Aster ocrinites, Miinster, 

 the difference being sufficiently well marked to prevent any confu- 

 sion of the two names. A very eminent authority, Prof. A. Agassiz, 

 thus writes on this subject**: — "We ought not to reject names dif- 

 fering so little as Moulinia, Moulinsia, Moulinsium, Cassidula, Cas- 

 sidulus, simply because they are likely to be mistaken for one 

 another ; in our present condition, with an infinite number of 

 genera, a difference, no matter how slight, should be sufficient 

 reason for retaining the name instead of coining a new one, which 

 is just as likely to fall into the same category, and resemble another 

 name in a different department to as great an extent." 



These quotations comprise all the published information I have 

 been able to gather concerning the history of Astrocrinites tetra- 

 gonus, Austin. 



I have now the pleasure of bringing under the notice of the 

 Society some small and highly interesting fossils lately discovered 

 by Mr. James Bennie, during his duties as one of the fossil-collec- 

 tors of the Scotch branch of H.M. Geological Survey. In doing 

 so I have to thank Prof. Eamsay, F.B.S., Director General of the 

 Survey, for permission, obtained through Prof. Geikie, P.R.S., to 



* Quart. Journ. Geol. Soc. 1848, iv. p. 293. 



t Index Pal. Nomenclator. , 1848, p. 1381. 



} Wiegmann's Archiv f. Naturg. 1851, p. 390. 



§ Keck, sur les Crino'ides du Terr. Carb. Belg., 1854, pp. 189 & 193. 



|| Cat. Brit. Foss. 2nd edit. (1854) p. 72. 



•jf Traite de Pal., 1857, iv. p. 295. 



** Eevision of the Echini, pts. 1 & 2 (1872), pp. 23, 24. 



