292 PROCEEDINGS OF THE ACADEMY OF [1881, 



9. MELOCRINUS Goldfuss. 



182G. Goldfuss. Petrefacta GermanijB, i, p. 197. 



1835, Agassiz. Mem. d. 1. Soc. des Sci. Natur, de Neuchatel, 1, p. 196. 



1841. Miiller, Monatsb, Berl. Akademie, 1, p. 209. 



1850, D'Orbigny. Prodr, de Paleont., i, p. 103, 



1852. D'Orbigny. Course Element., ii, p, 140. 



1855. Roeraer. Lethsea Geogn. (Aiisg, 8), p. 250. 



1857, Pictet. Traite de Paleont., iv, p. 325, 



1867. Schultze. Mon. Echin. Eifel Kalk,, p. 61. 



1875, Hall, Geol. Rep. Ohio, Paleont., ii, p. 158. 



1878. Angelin. Iconogr. Crin, Suae, p. 19. 



1879, Zittel. Handbuch d. Palaeontologie, i, p. 371, 

 Syn. Otenocrintis Bronn, 1840, Jabrbuch, p. 54. 



Syn. Ctenocrinus Miiller, 1855. Verhandl, Naturli, Verein, xii, 

 p. 16, 



Syn. Castanocrimcs Roemer, 1855, Lethsea Geogn., ii, p. 252, 



Syn, Mariacrinus Hall (in part), 1857, Paleont. N. York, iii, p. 104, 



Syn. Cytocrinus Roeraer, 1860. Silur. Fauna West. Tenn., p. 46. 



Syn. Clonocrinus Oehlert, 1879 (not Quenstedt), Bull, Soc. Geol. 

 de France (ser. 3), vol. vii. 



Syn. Tuvbinocrinites Troost. List. Crin. Tenn,, 1850 (not defined). 



Syn. Astrocrinites Conrad. Cat. Geol. Rep, of 1840 41 (not Cum- 

 berland, 1S26 ; nor Austin, 1843 ; nor Asterocrimis Lyon, 18o'7 ; 

 nor Mlinster, 1839). 



The genus Melocrinus holds the same relation to Ilariacrinus 

 as Steganocrinus to Actinocrinus^ and as Eucladocrinus to Platy- 

 crinus. In all of them the construction of the body remains 

 almost unchanged, while a remarkable modification takes place in 

 the brachial appendages, which are extended into free rays with 

 an indefinite number of radials, which give off the arms laterall3% 



This character separates the genera of the three groups A'ery 

 distinctly and uniforml3^ 



Several attempts have been made to establish sub-divisions for 

 Melocrinus. Roemer, in 1865, proposed the name Castanocrinus 

 for species with a central or subcentral anal opening, retaining 

 Melocrinus with M. hieroglyphicus Goldf. for species with a 

 lateral opening. A critical comparison of all the species leads us 

 to doubt whether that division can be cari'ied out practicall}'. 

 We agree with Shultze, Mon,, p. 63, that the proboscis — anal tube 

 — is never central, and in this genus in no case actuall}'^ lateral ; 

 but that its direction is more or less excentric in all species. 

 Neitl)er can the presence or absence of interaxillary plates, unless 

 accompanied by other distinctive characters, be considered for a 



