1879.] NATURAL SCIENCES OP PHILADELPHIA. 235 



apparatus. Whether the above described pores communicated 

 with these chambers cannot be determined from the fossil, but we 

 may perhaps infer this from their position, and also that the 

 chambers themselves were or contained organs similar to those 

 described as hydrospires in other groups of the Crinoidea. 



Folded sacs or parallel tubes, as in the Blastoids, have not 

 hitherto been noticed in the Pahieocrinoidea. That they existed 

 in some groups of the latter is almost certain. The so-called 

 "consolidating apparatus" of Cupressocrinus (PI. 17, Fig. 3) is 

 in our opinion a true set of hydrospires, arranged in pairs exactly 

 as in Blastoids, but spreading out horizontally instead of verti- 

 cally. Angelin (Iconogr. Crin., PI. VIII. Fig. 7, a, b) figures a 

 Crotalocrinus, in which the consolidating apparatus or hydro- 

 spires, as we believe is most excellently preserved. Even the 

 inner tubes can be traced, and, if there existed still a doubt 

 Avhether the closely related Cupressowinus had its ventral side 

 firmly closed, Angelin's figure, PI. VIII. Fig. 6, ought to remove 

 it. There seems to be in Crotalocrinus not only a solid integu- 

 ment covering the entire ventral disc and inclosing the hydro- 

 spires, but we judge from Fig. 7 of the preceding plate, that the 

 oral centre or median space between the hydrospires had even a 

 double covering. 



It seems to us that there can scarcely be a doubt but that the 

 consolidating plates of Cyathocrinus (PI. 17, Fig. 2) are homo- 

 logous with the oral plates of the Pentacrinoid larva (PI. 17, Fi<j\ 

 1), and ought to be designated as such; and further, that the 

 so-called consolidating plates of Cupressocrinus are the homo- 

 logues of the deltoid pieces of the Blastoids (PI. 17, Fig. 4). 

 It will be seen that all four occupy the same relative position in 

 the respective types. There are five interradial plates, which join 

 at their sides, extending inward, but so as to leave an opening at 

 the oral centre. The affinities, indeed, are so striking that we 

 think it not unreasonable to suppose that the ln'drospires are 

 metamorphosed oral plates. The construction of the deltoid 

 pieces is very complicated, only the median or deltoid portion 

 being visible externally. Thej' are extended laterally, in spade- 

 shaped appendages (PI. 17, Fig. 4), which pass under the am. 

 bulacral fields and are hidden by them. To these appendages the 

 folds of the hydrospires are attached, being suspended on each 

 side of the ambulacrum, or modified arm, and partly covered by 



