INVEETEBEATES. 5] 9 



Subgenus SOAPHIOCEINUS, Hall. 



SCAPHIOCRINTJS TJNICTJS. 



PI. iO, Fig. 1. 



Scaphiocrinus unicm. Hall, 1SG1. Prelim. Descr. New Crinoidea, p. 8. S. unicus, Meek and Worthen, 

 1872, Geol. Survey of 111., Vol. V, p. 493, PI. 15, fig. 5. 



" Body broadly cup-shaped, with a deeply depressed base, somewhat 

 abruptly spreading at the summit of the first radials. Basal plates and 

 lower ends of the subradials forming the bottom and sides of the cavity. 

 Arms dividing on the second radial plate; each division bifurcating 

 twice and rarely three times. The anterior ray has a single arm, which 

 is undivided throughout. This single arm is a strongly distinctive char- 

 acter." 



The above is the original description of this species as published in 

 18G1, and the figure of an unique specimen is introduced here, showing 

 the full form of the ventral tube, with a well marked anal opening on 

 its anterior side, situated about midway between the apex and base of 

 this organ. The ventral tube is strongly inflated at the upper extremity, 

 and is surmounted by three or more strongly pointed spines. So far as 

 I am aware this and the Poteriocrinus Coreyi are the only examples of 

 crinoidea yet discovered showing the position of the anal opening in 

 the Poterioerinidce. 



Position and locality : Crawfordsville, Ind., Keokuk group, Lower 

 Carboniferous. I am indebted to Prof. E. O. Hovey, of Wabash Col- 

 lege, for this unique specimen. 



Scaphiocbinus abnormjs, Worthen. 



PL 31. Fig. 6. 



Body tmncato-obconic, basal plates small, and concealed in the col- 

 umnar depression ; subradials not well shown in our specimen, in which 

 the body plates are somewhat distorted by pressure; two of the radial 

 pieces longer than wide and hexagonal, the others about as wide as long 

 and pentagonal, each giving support above to a second radial piece. 

 Second radials about as wide as long, constricted about the middle, and 

 two of them supporting two arms on their upper sloping sides, which 

 continue single as far as they can be seen. On two of the other rays, 

 and probably on all three of them, a single arm proceeds from their 

 upper oblique margins, and not dividing, make but seven or eight arms 

 altogether. Arms composed of a single series of stout, wedge-shaped 

 pieces, giving off numerous pinnuhe from their inner margins, com- 



