1886.] NATURAL SCIENCES OF PHILADELPHIA. T5 



ponding radials of adjacent rays meet again above the inter- 

 radials, just as in some species of Ichthyocrinus and Batocrinus. 



The genus differs from GrotalociHnus^ its nearest ally, in the 

 absence of the reticulate arm structure, although there is a 

 lateral connection between the arm branches for some distance 

 above their bases ; also in the alternate arrangement of adjacent 

 rows of arm joints. The construction of the ventral covering is 

 apparently the same in both forms. There is, however, a differ- 

 ence in the mode of union of the calyx plates, the lines of 

 junction in Enallocrinus, showing strong indications of an artic- 

 ulation, as we judge from Angelin's figs. 1, 4, and 4 a, of PL xxv. 

 Angelin united the two types of Hisinger under his first species 

 U. scriptiis^ and described one new species. 



Generic Diagnosis. The calyx differs but little from that of 

 Grotalocrinus, and when the arms are spread this produces a 

 similar discoid figure, and lanceolate areas similar to those of 

 that genus. The calyx is depressed, broadly expanding, com- 

 posed of thick plates with deeply beveled sutures, indicating a 

 union by articulation. Base dicyclic ; symmetry bilateral ; under- 

 basals 5, depressed, linear; basals 5, large, hexagonal, angular 

 above, except on the anal side ; radials 2X5, the first one wide, 

 with its distal face occupied by a deep lunate excavation, which 

 is filled by the second radial and the two first arm joints. Lateral 

 faces of first radials deeply incurved between the arm bases, and 

 meeting tegminal plates on the ventral side. Second radial 

 trigonal or pentagonal, and on its superior sloping margins the 

 arms bifurcate as in Marsupiocrinus. The first arm-joint small, 

 linear, sometimes coalesced with the second ; the second small, 

 axillary ; arms broad, thick, composed of short uniserial joints, 

 dichotomizing frequently. The branches are laterally connected 

 near their bases, but throughout the greater portion of their 

 length are free. Arm joints alternating with those of adjacent 

 rows. As in Grotalocrinus, the outer sides of the peripheral rows 

 of the rays are the thickest, and the deep inward curvature of 

 their exterior lateral faces leaves similar large petaloid or lanceo- 

 late areas. The exterior ventral margins of the incurved radials 

 of the first and higher orders, and some of the lower arm joints, 

 connect with the plates of the ventral covering, which is of a 

 similar nature as that of Grotalocrinus. Ambulacral furrow deep, 

 dichotomizing with the arm branches, bordered by two rows of 



