494 MB. p. H. CABPEITTEE ON NEW 



doubted by Schliiter*; and I have myself had some hesitation in 

 regarding it as equivalent to Antedon, Actinometra, and JBroma- 

 cJiocrinus f. For there is no definite character, except the sim- 

 plicity of the rays, which can separate OpMocrinus from the ordi- 

 nary ten-armed Antedon ; and in one of the three known species 

 of the ten-rayed Fromachocrinus the rays divide, so as to form 

 twenty arms ; while in the two others there are ten undivided 

 rays. But this character alone would hardly justify the separa- 

 tion of the simpler type of Fromachocrinus from the twenty- 

 armed form ; while I have an abnormal specimen of an Antedon 

 with only nine arms, owing to one of the rays not dividing, which 

 is the case with all the rays of Ophiocrinus. 



Nevertheless it sometimes happens that a character which is 

 only of specific yalue in one type may be of generic value in ano- 

 ther ; and as four recent species of Ophiocrinus are known which 

 range from Japan into the South Pacific Ocean (lat. 37° S.), 

 together with the fossil from the Neocomian of Switzerland, the 

 simplicity of the rays appears to be a character of some morpholo- 

 gical importance ; and I am therefore disposed to admit the 

 generic value which was originally assigned to it by Semper. 

 Unfortunately, however, this type cannot continue to bear the 

 name by which it has been hitherto known. For Salter, fifteen 

 years previously to Semper's description of Ophiocrinus, had 

 designated by the same generic name an obscure Crinoidfrom the 

 Devonian of South Africa ; and the confusion thus existing was 

 increased by the posthumous publication, in 1878, of the late 

 Prof Angelin's * Iconographia of the Swedish Silurian Crinoids,' 

 in which the name Ophiocrinus is connected with a third and 

 totally distinct type. 



Prof. Semper's genus being thus preoccupied, I propose to call 

 the type JEudiocrinus (evdios, calm), in allusion to the fact that all 

 the recent species of it which are known to science are limited to 

 the Pacific Ocean. 



In its central mouth and in the structure of its calyx JEudio- 

 crinus is essentially an Antedon. But the sacculi which are 

 usually so abundant at the sides of the ambulacra of this genus 

 are not so constant in Eudiocrimis. JE. indivisus has numbers 

 of them, while they are scanty in E. varians, and altogether 



* " Ueber einige astylide Crinoiden,"'Zeitschr. der deutsch. geolog. Gresellsch. 

 Jahrg. 1878, p. 40. 



t Quart. Journ. Geol. Soc. vol. xxxvi. p. 41. 



