1885.] NATURAL SCIENCES OF PHILADELPHIA. 361 



Fig. 6. Cyathocrinuxmultibrachiatus. Ventral surface showing the perisomic 

 plates, portions of the interradials, and the summit plates, the latter in 

 process of resorption. 



Fig. 7 a. A portion of an arm of the same species. Side plates and cover- 

 ing pieces in position (enlarged). 



Fig. 7 6. A portion of the same specimen still more enlarged. 



Fig. 8. Portion of an arm of Symbathocrinus dentatus, showing the ventral 

 furrow and its covering. 



Fig. 9. Ventral aspect of Symbathocrinus Wortheni after removing the 

 upper half of the first brachials. 



Fig. 10. Showing the inner floor of the summit plates in Symbathocrinus 

 Wortheni. Seen from below, in a transverse section through the first 

 brachials. 



Fig. 11. Cross section of arms and ventral tube at a point midway between 

 the base and tips of the arms, from the same specimen. 



EXPLANATION OF PLATE V. 



Fig. 1. Raplocrinus mespiliformis Goldfuss. Ventral aspect, showing the 



interradials and anal opening. 

 Fig. 2. Posterior view of the same specimen. 

 Fig. 3. Distal face of the bifurcating primary radial of Forbesiocrinu* 



nobilis, showing its two axial canals. 

 Fig. 4. Proximal face of the same. 



Fig. 5. Lateral face of an interradial of the same species. 

 Fig. 6. Ventral aspect of an internal cast of Batocrinus Christyi. The 



dark places represent the pillars suspending the perisome, and the 



radial ridges the subtegminal ambulacral tubes. 

 Fig. 7. Ventral aspect of Cyathocrinus iovensis. All summit plates bisected 



or partly resorbed. 

 Fig. 8. Internal view of the central part of the vault, showing a portion ol 



the perisome, and the peristomeal area beneath the centre of the oral 



plate, whose sutures are visible in the deeply shaded portion. The 



figure does not show the specimen as far as the arm bases. 

 F \g. 9. Ventral aspect of an internal cast of Platycrinus. The interradials 



forming a continuous ring around the proximals, surmounting the 



covering plates, which emerge from beneath the vault close to the arm 



bases. 

 Fig. 10. Bclemnocrinvs typus "White. Side view of a perfect specimen, 



showing the porous ventral tube and the arrangement of arms and 



pinnules. 

 Fig. 11. Belemnocrinus floriftr W. & Sp. Side view of type specimen, 



showing the arrangement of arms and pinnules ; the ventral tube, and 



the position of the cirrhi. 

 Fig. 12. Symbathocrinus Wachsmuthi M. & W. Ventral aspect, showing 



the arrangement of the summit pieces and the anal plate. 



