FOSSILS OF THE BUKLIXGLOX GROUP. 389 



are simple. The usual vermicular markings of the body plates in the 

 specimen are well defined, and on the upper anal and vault pieces, as 

 -well as on those composing the proboscis, and even on the spines, the 

 whole surface of which is occupied by rather coarse granules. As in 

 the other species of this group, the arms of which are known, they ex- 

 tend at their bases, first horizontally outward, or even a little downward, 

 and then curve upward. 



It is probable that this specimen, with simple instead of bifurcating 

 vault spines, and somewhat differently divided arms, may be specifically 

 distinct from the A. rlivergens. If so, we would propose to call it Ampho- 

 racrin m m ulliramosits. 



AMPHORACRIXUS ? SPINOBRACHIATUS, Hall (sp). 



PI. 6, Fig. 5. 

 Actinocrinus tpinobrachiatut, Hall, I860. Supp. Geol. of Iowa, p. 6. 



(Burlington Limestone, Burlington, Iowa. Mr. WACHSMUTU'S collection.) 



GEXUS GILBEKTSOCKLNTJS, Phillips. 



SUBGEXUS GoxiASTEROiDOCROUS, Lyon & Casseday, 1859. 



Syn. Trematocrinm, Hall, 1860. 



GOXIASTEROIDOCRIXUS TEXUIRADIATUS, M. and W. 



PI. 11, Fig. 1. 

 Qoniasteroidocrinus tenuiradiatu-s, MEEK and WORTHES. Proceed. Acad. Nat. Sci., Phila., 1869, p. 75, 



THE only specimen of this species we have seen is too 

 much crushed to admit of a detailed description of the 

 structure of its body. It evidently attained a medium 

 size, however, and has unusually long, slender, pseudo- 

 brachial appendages, or false arms; while its subradial 

 pieces are produced into short, pointed spines. Its false 

 arms are each composed, near the body, of a double series 

 of alternating semi-elliptic pieces, which are joined together 

 l>y their straight sides, and each pierced by a small central 

 canal. At a distance of about three or four pairs of these 

 pieces from the body, each series of pieces diverges from the 

 other at an angle of about fifty degrees, thus forming two 



