1887.] NATURAL SCIENCES OF PHILADELPHIA. 103 



ill early life through the Inadunata stage, seems to us beyond dis- 

 pute, and we think we may assert that they were for a time in a similar 

 condition to Haplocrmus, with one interradial plate disposed ven- 

 trally. Limiting our observations among the Camarata to the 

 Platyerinidae, we find, so far as we know, their simplest forms repre- 

 sented by the two early genera Culicocrinus and Coccocrinus, which both 

 have two rows of plates interradially disposed, the one resting with- 

 in the circlet of the other. In Culicocrinus,^ if Miller's figure is 

 correct, the first row of these plates consists of five rather large pieces, 

 one to each interradius, which connect laterally with the j^rimary 

 and secondary arm plates, so as to make them radials and integral 

 parts of the calyx. Those of the second row which are triangular 

 meet laterally and close the center, apparently without any additional 

 plates. 



Of Coccocrinus two species are known. Coccocrinus bacca has 

 three interradials in the first row, which have a strictly ventral posi- 

 tion, C. rosaceus ap23arently but one, which is more erect. In both 

 species the plates extend to the height of the third primary radials, 

 and probably higher. The inner row of plates is only known in C. 

 rosaceus, and these, like those of Culicocrinus, are subtriangular, 

 but, unlike them, do not connect laterally with one another, nor do 

 they meet in the center. There is a lateral slit between them 

 all the way to the arm openings, and at the center an open space, 

 which in the fossil is not filled by any further structures. In C bacca, 

 as stated, the inner plates have not been preserved, but we scarcely 

 doubt that similar plates were present, for we find in a radial 

 direction between the outer plates of the first row, very conspicuous 

 slits, which correspond to those of C. rosaceus. 



The outer plates, in the two genera, were regarded by Carpenter 

 as calyx interradials, the inner ones as orals, and these he took to 

 be the homologues of the five large ventral plates of Haplocrinus, 

 and of the proximals in other groups. 



We admit that Coccocrinus and Culicocrinus probably are morph- 

 ologically in a similar condition, and represent early stages in the 

 phylogeny of the Palaeocrinoidea like Allagecrinus and Haplocrinus, 



^Through the kindness of Prof F. Roemer, we received a most excellent 

 gutta percha cast of a CuUcocrimis with arms, from a mould in the Mineralogical 

 Museum of Breslau, but not showing the ventral covering. Miller's original fig- 

 ures of the ventral covering, Lethea Geognostica of 1855, Taf. VIII, figs. 1 and 

 2, we are informed are much restored, and the arrangement of the plates, as there 

 given, not altogether reliable. 



