1886.] NATURAL SCIENCES OP PHILADELPHIA. 103 



homologous with those of other Crinoids, there being six or 

 more of them to each arm plate, given off from each side, in 

 place of one alternately arranged, a structure similar to that of 

 the so-called pinnules of the Blastoids. Also their ambulacra, 

 aside from not being recumbent and forming no part of the calyx, 

 resemble closely those of the latter group. By removing the 

 lancet piece and side pieces in Pentremites, and exposing the 

 sinus, it will be found that the inner sides of the limbs are con- 

 structed almost exactly as the inner walls of the arm-grooves in 

 Cupressocrinus, as seen by a comparison with Schultze's figure in 

 his Monograph, PL ii, figs. 7 and 11. There are in both struc- 

 tures deep, rounded transverse grooves, alternating with ridges 

 which are truncate above, and each one of them is provided 

 lengthways with a small furrow at the top. These furrows do 

 not extend to the full length of the ridge, but are provided at 

 their outer end with an articular facet for the attachment of a 

 pinnule. The pinnules at their base do not touch laterally, but 

 leave a small open space in the direction of the lateral grooves. 

 These grooves form the outer half of a pore, similar to the 

 hydrospire pores of the Blastoids, and like the latter probably 

 are communicating in a similar manner with hydrospires, lodged, 

 however, within the arm grooves and not within the calyx. 

 Schultze's figures 1 h and 1 i, in our opinion, are incorrect. 

 Cupressocrinus certainly had no such " Tentakel-Furche " as 

 here represented, and we doubt if the genus possessed such 

 minute irregular covering plates, either along the perisome or 

 within the arms. 



Generic Diagnosis. Dorsal side of the calyx basin-, cup- or 

 bell-shaped, composed of rather large, heavy plates; when the 

 arms ai-e attached and closed, the form is ovoid or pyramidal. 



The basals consist of five equal, pentagonal pieces, which 

 enclose an equilateral, undivided disk, formed by a coalescence 

 of the underbasals, or, according to others, by the upper stem 

 joint which became enlarged and as such took the place of the 

 underbasals in other genera. 



Radials five, of similar form, wider than high, pentangular ; 

 the upper margins truncate, and forming a horizontal line. They 

 are succeeded by five very short pieces, of the same width, which 

 Schultze designated as " articularia " and as parts of the calyx. 

 The arms are wide, simple, closely folded together, and composed 



