1888.] NATURAL SCIENCES OF PHILADELPHIA. 367 



ment of the plates covering the visceral cavity is extremely irregular, 

 scarcely any two plates being alike. There is neither a central 

 plate, nor anything that might be compared with the four large 

 proximals, and no plates corresponding to, or which might be identi- 

 fied as covering plates until the region of the arms is reached. In 

 PI. VIII, fig. 6, the plates appear ornamented by small nodes up to 

 the second bifurcation of the ray, and a similar ornamentation cov- 

 ers the anal structure, of which portions are visible. This ornamen- 

 tation is so marked, .and gives to this part of the figure such a total- 

 ly different aspect from the higher branches of the rays, in which it 

 is entirely absent, that we regarded it as a vault, from underneath 

 which the covering plates emerged. The whole figure gives one the 

 impression that it was made from a very perfect specimen, in which 

 the minutest details of structure were exceptionally well preserved. 

 The other figure-7-on the same plate exhibits a similar vault, but 

 with less elaboration of ornament and surface details. Covering 

 plates are here visible only upon the parts which extend beyond the 

 limits of the calyx, nor is there any trace of proximals or central 

 plate. 



Figure 3a, of PI. VII, which is said to represent " j)ars perisomatis 

 ventralis " of Enallocrinus scriptus, shows a complete uninterrupted 

 covering of the whole ventral surface of the calyx and portions of 

 the rays. As in the other figures, the plates are wholly wanting in 

 definite arrangement, no summit plates can be discovered, and the 

 covering pieces, as before, begin at the periphery of the calyx. 



Another figure of the same species, apparently from a most beau- 

 tifully perfect specimen, to judge from the drawing, is given on PI. 

 XXV, fig. 2. It is stated in the explanation of the plate to be the 

 same specimen as fig. 1, seen from above, and there is no reference to 

 any imperfection or restoration. It appears to show all the plates 

 of the ventral covering from the center of the summit to a long dis- 

 tance out upon the arms. In this figure, as in the preceding, there is 

 a complete absence of any regular plan of arrangement among the 

 plates forming the ventral part of the calyx. It would be impossi- 

 ble by any degree of imagination, to identify among them anything 

 like summit plates or covering pieces, the latter commencing beyond 

 the limits of the calyx. The plates are generally represented as no- 

 dose, and those toward the middle as the largest, but beyond this 

 there is nothing in the figure to distinguish any of them. 



