52 ON THE MOBPHOLOGT OF THE CTSTIDEA. 



EXPLANATION OF PLATE I. 



Fig. L Analysis of the dorsal cup of Hemicosmites pyriformis. Copied from 

 Von Buch (Abhandl. Berlin Akad. 1844, Taf. ii. fig. \0).—ib, 1-4, 

 infrabasals; b, 5-10, basals; r, 11, 12, 14-17, radials ; i, 13, 18, A, 

 interradials. 



Fig. 2. Aualj-sis of the dorsal cup of Caryoerinus wnatus. Copied from Hall 

 ('Palipont. New York,' vol. ii. pi. 49. fig. ly). — Lettering as in Fig. 1. 



Fio'S. 3-7. A-E, the five rays ; 1-4, infrabasals ; 5-9, basals ; 10-14, radials ; 

 15-19, first series of perisomic plates (interradials ?). — N.B. The num- 

 bering of the plates is not always identical with that employed in the 

 original figures. 



Fig. 3. Analysis of the dorsal cup oi Echinoencrinus annatus, var. Copied from 

 Forbes (Mem. Geol. Survey, vol. ii. pi. xix. fig. 5) with the addition of 

 a pore-rhomb, occasionally present on plates 12-18. 



4. The AovBSiicw^oi Echinoencrlnusangidosus, developed laterally. Copied 



from Von Buch (Abhandl. Berlin Akad. 1844, Taf. ii. fig. 7). 



5. Analysis of the dorsal cup of Callocystis Jewetti. Copied from Hall 



(' Paleontology of New York,' vol. ii. pi. 50. fig. 11). 



6. Analysis of the dorsal cup oi Lepadocrinus Gehhardi. Copied from Hall 



(' Palaeontology of New York,' vol. iii. pi. 7. fig. 23). 



7. Side view of the calyx of Cystoblastus Leuchtenbergi. Copied from 



Volborth (Mem. St. P^tersbourg Acad. 1870, tome xvi. no. 2, fig. 14). 

 — b, osculum ; c, excretory (?) opening, 



8. The dorsal cup of Glyptocystis multipora, developed laterally. Copied 



from Quenstedt ' Atlas, Asteriden und Encriniden,' tab. 113. fig. 83. 



9. The dorsal cup of Cryptocrinus cerasus, developed laterally. Based on 



Von Buch's figure (Abhandl. Berlin Akad. 1844, Taf. ii. fig. 5). 



Figs. 10, 11. Internal and external views of the oral pole of Pyrocysfis deside- 

 rata. Fig. 10 shows the subtegminal ambulacra (hydrophores, Sar- 

 rande), and fig. 11 the low pyramid of oral plates above the mouth. 

 Copied from Barrande (Syst. Silur. de Boheme, vol. vii. pi. 29. figs. 

 32, 33). 



Fig. 12. The oral pole of Aristocystis Bohemica. Copied from Barrande 

 (Syst. Silur. de Boheme, vol. vii. pi. 9. fig. 17). — a, mouth ; b, anus ; 

 c, genital pore ; d, excretory (?) opening. The genital pore is on the 

 edge of the anal opening. 



13. A similar view of another specimen, with the genital pore further re- 

 moved from the anal opening. Copied from Barrande (Syst. Silur. 

 de Boheme, vol. vii. pi. 9. fig. 6). 



14. Summit of Caryocrmus ornaius, from a specimen belonging to Mr. 

 Wachsmuth. — b, anus; o, oral plates ; r (11, 12, 14—17), radials ; i(13, 

 18), interradials. 



15. Portion of the summit of Glyptosphara Leuchtenbergi, showing — a, the 

 low pyramid of oral plates above the mouth ; b, the anus ; c, the 

 genital pore ; d, the excretory (?) opening, possibly a madreporite. 

 From Quenstedt 'Atlas, Asteriden und Encriniden,' tab. 114. fig. 10. 



