p. H. Carpenter — Notes on Oreaster hulbiferus. 531 



" This genus is synonymous with Pentaceros of Linck (but that 

 name is objectionable, since it has been applied to a genus of Fishes 

 by Cuvier and Valenciennes). It formed part of Goniasfer as defined 

 by Agassiz. The fossil species are found in the Upper and Lower 

 Chalk ; and some of them bear considerable affinity to existing forms. 

 Those now living are all tropical, and often of great size." 



Miiller and Troschel proposed the genus Oreaster as a substitute 

 for Pentaceros, Linck, on the grounds mentioned by Forbes. Before 

 their time, however, the late Dr. Gray had transformed Linck's 

 name into that of a family PentacerotidcB, in which he included such 

 very dissimilar forms as Echinaster, Ophidiaster, and Pentaceros. 

 According to Prof. Edm. Perrier,' it is therefore necessary to sub- 

 divide this into three small families ; but though retaining Linck's 

 generic name, he prefers to give the name Goniasteridce to the last 

 of these, in which he places Pentaceros, because the fourteen genera 

 which he includes in it are very nearly those that were formerly 

 comprised in the genus Goniaster, Agassiz. Prof. Claus,^ however, 

 groups these fourteen genera into three more families, and names 

 one of them Oreasteridte, though using Linck's generic name. This 

 is considerably older than the time of Cuvier and Valenciennes, and 

 therefore should have the right of priority ; while the fish-genus of 

 the same name proposed by these naturalists seems to have fallen 

 out of use, as it is not to be found in the index to Claus's Grundziige. 



Mr. A. Agassiz,^ writing in 1877, employed Pentaceros rather than 

 Oreaster, as does Prof. Zittel in his well-known " Handbuch der 

 Palaeontologie " (page 427); though Dr. Liitken, of Copenhagen, 

 who has such an extensive acquaintance both with Echinoderms 

 and with Fishes, has recently revived Oreaster again.* It seems 

 probable, however, that Linck's claims will prevail, and that the 

 genus will be known in this country as Pentaceros, just as it is in 

 France, Germany, and America. The subject will doubtless be 

 fully considered by the accomplished naturalist who is working out 

 the Star-fishes collected by the "Challenger"; and till his report 

 appears, at any rate, palgeontologists may continue to employ 

 Forbes's nomenclature. He gave the following description of the 

 sjDecies represented in our Plate. 



Oreaster hulbiferus, E. Forbes. Plate XII. 



E. Forces in Dixon's Geology of Sussex, 1st edition, 1850, p. 328, pi. xxiv. 

 fig. 27 ; 2nd edition, 1878, p. 363, pi. xxiv. [27] (fig. 7 in en-or) fig. 27 on 

 plate. Mem. Geol. Svurv. vol. ii. p. 468. 



" Disk very convex, covered in the centre with flat, many-lobed, 

 punctated plates, some of which are very large. Opposite the 

 origin of each ray is a large tubercular, very convex conic plate, 

 with a wide and lobed base. The surface of all these plates is punc- 

 tate ; a few similar plates, but less, and more regular in form, run 



' Eevision des Stellerides, Paris, 1875, pp. 16-17. 



* Grundziige der Zoologie, 1880, p. 342. 



2 North America Star-fishes, Cambridge, U.S. 1S77, p. lOS. 



* Dyreriget. (The Animal Kingdom). Textbook oiZoolo;;\- No. 1, Copenhan-en, 

 1882, p. 613. "■ i o > 



