IN THE MORPHOLOaT OP THK CYSTIDEA.. 23 



sehr aufiallige Analogie mit den paarigen Oeffnungon ocler rielmehr Kanalen ira 

 Scheitel der Blastoideen ins Auge zu fassen sein. Sie miissen aber auch zuni 

 Theil die Funktionen von Mund und After erfiillt haben." 



It seems to me that tiiere can be little doubt as to the ambu- 

 lacral nature of these six openings in the summit oiJiiglanclocrinus. 

 They were not related to hydrospires, as Von Koenen seems to 



r 



Summit of Juglandocrinus c'rassus. Copied from Von Koenen (N. Jahrb. f. 

 Mineralogie &c. 1886, Bd. ii. Taf. ix. fig. 3). The dotted lines 

 indicate the course of the subtegminal ambulacra, which opened 

 externally by three pairs of pores. (N.B. One of these pairs has been 

 accidentally omitted in Von Koenen's original figure, in which the 

 three superambulacral plates are marked to). — Plates 11-18, radials 

 and interradials of the dorsal cup as in Figs. I., II. ; Gc, H, oi, peri- 

 stomial plates (orals ?). 



suggest ; but the food-particles entered through them on their 

 way to the central mouth, just as they did at the arm-openings 

 of the Paleeocrinoidea. If the comparisons drawn above between 

 the ambulacra of Juglandocrinus and those of Garyocrinus and 

 Hemicosmites be in any way valid, then the anus of the former 

 type should be looked for somewhere in the neighbourhood of 

 plates 15 and 16. It would also seem to follow that the central 

 plate and the three super-ambulacral orals of Caryocrinus corre- 

 spond respectively to the central plate and the three plates m of 

 Jucjlandocrinus. I have some doubt *, however, as to whether 



* One possible view would be to regard the two anterior plates, n, which rest 

 upon the two interradials 13, 18, as representing the anterolateral orals of 

 CaryocTinus, and the posterior plate n as an anal summit-plate. But if the 

 central plate could be disestablished, as that of Haplocrinus was, there would 

 then be but six plates (orals ?) in the summit, just as in Hemicosmites (fig. I.). 



