288 PROCEEDINGS OF THE ACADEMY OF [1881. 



them ; the iiitermdial and anal plates also similar in their form 

 and arrangement ; bnt the first interradial and the second series 

 of anal plates extend to the top of the tertiary radials, and support 

 directly the vault pieces. 



Dome elevated, conical, extended into a large, almost central 

 anal tube ; vault pieces more or less nodose, the apical plates 

 somewhat larger, hut not so distinct as in Agaricocrinus^ and 

 pushed more towards the anterior side. Length of anal tube 

 unknown. 



Arms large, simple so far as known ; two arms from each ray, 

 with sometimes three on one or both posterior raj^s. 



Geological Position^ etc. — The only known species occurs in the 

 Warsaw limestone. 



I860. Alloprosallocrinus conicus Lyon and Cass. (type). Proc. Am. Acad. Arts 

 and Sci., vol. v, p. 29. Shumard, 1866, AUoprosallocr. (subg. of Actinocr.) 

 conicus, Cat. Pal. Foss., pt. 1, p. 352. Warsaw limest. Hardin and Allen 

 Cos., Ky. 



c. Melocrinites. 

 7. MARIACRINUS Hall. 

 (Revised Iby Wachsm. and Spr.) 

 1859. Hall. Paleont. New York, vol. iii, p. 104. 



Mariac7nnus in its original form, with M. nobilissimus, M. pauci- 

 dactylus and M. p/achidactylus Hall as types, were shown by 

 Schultze, Mon. Echin. Eifel. Kalk., p. 61, to be identical with 

 Melocrinus Goldfuss. This is undoubtedly correct with regard 

 to those species, but Hall described two other species, M. plumosus 

 and M. ramosus, which in their arm-structure differ so essentially 

 from the former, that we think it proper to separate them and 

 reconstruct the genus Mariacrinus with M. plumosus as the type. 

 To these two species we add Melocrinus angustatus Angl., and 

 Glyptocrinus Carleyi Hall, which latter we find to have four 

 basal plates instead of five, and no underbasals. 



The genus Mariacrinus^ as we propose to define it, includes 

 only species in which the two main divisions of the ray are longi- 

 tudinally separated, forming two free and equal parts, contrary to 

 Melocrinus^ in which the main branches are laterally connected. 

 Hall already noticed this peculiarity in the arm-structure or 

 Melocrinus plumosus, and he very correctly homologized the two 



