NEW AGELACRINITES 185 



the name can not appropriately be applied to Siluric forms like 

 A. cincinnatiensis. 



Let us take a short step backward. Prof. Hall in 1868^ had 

 described an agelacrinite from the Kaskaskia (Chester) limestone 

 (Kaskaskia 111.) as Agelacrinites kaskaekiensis. 

 The figure of the specimen represented five long and slender 

 arms, all directed up and over to the left (sinistral or contrasolar), 

 but the description ascribes six rays to the fossil. Meek 

 and WoTthen having the type ispecimen before them, pointed 

 out that there were but five arms, and that, if there was an 

 appearance of a sixth, it was due to an imperfection in the speci- 

 men. Prof. C. A. Rolfe of the Illinois state university has 

 kindly provided me with a photograph and squeeze of this 

 original, from which it is clear, not only that ^^=<:f=^^^^^ 



there are indeed five rays, but that they are /^^^^^^^^^ 

 njot all contrasolar, as represented by Hall Mj^f^^'^^^^^i:^^^^^^ 

 and also in the figure reproduced by Keyes,^ llWw^^^^^^^^f 

 -but that only four are contrasolar, while the ^^n^Q:^^^^^^ 

 fifth is solar; and in this respect at least the ^^^^^^^^^ 

 species conforms to the type of Lepidodiscus. ^<^^^^^ 



Fig. 1 The original specimen 



To the other features of its structure subse- of^- kaskaskiensis Haii 



showing R 1-4 contrasolar, 



quent reference will be made. r s soiar, and the mosaic 



T ^ ooo T-TT ,1 T-.,.no., , -. pavement of the interradll. 



In 1883 YVorthen and Miller^ introduced Natural size 

 the generic term, Echiuodiscus, with a single species, E. optatus, 

 from the Chester limestone of Illinois. The single figure given 

 of the species, and all that has ever been presented, shows what 

 is alleged to be a segment of the aboral surface. Of itself it 

 serves to define nothing, affording no clue either to generic or 

 specific structures. As establishing either species or genus it 

 is practically worthless. Notwithstanding this fact, the defini- 

 tion given of both species and genus is full and clear, describing 

 all the main features of the theca and ambulacra. One can not 

 fail of conviction, nor therein be far from the truth, that in the 



1 Geol. Iowa. v. 1, pt 2, p. 696, pi. 25, fig. 18. 



2 Geol. Missouri. Pal. 1894. v. 4, pt 1, p. 133, pi, 18, fig. 3. 

 a Geol. sur. 111. 8:335, pi. 31, flg. 9. 



