248 Prof. J. Miiller on the Structure of the Echinoderms. 



are caeca, which are indeed connected with the abdominal cavity, 

 but are perfectly closed externally. 



The calycine pores of Caryocrinus are equally without relation 

 to the arms ; and thence, though differently distributed, resemble 

 the anambulacral calycine pores of Pentacrinus. They occupy 

 the antambulacral part of the calyx behind the arms as far as 

 its base. 



Most Cysti deans [Cryptocrinites cerasus excepted) possess 

 calycine pores, which are distributed over a greater or smaller 

 part of the calyx without radiation and in a very peculiar manner. 

 In those forms with calycine grooves, as Protocrinites and Sphce- 

 ronites Leuchtenbergiiy these pores again appear to be anambu- 

 lacral, since, like the anambulacral pores of Pentacrinus, they 

 are disposed in the arese external to and between the ambulacral 

 grooves ; here, however, their distribution is far wider, since 

 they extend as far as the base. 



Two principal divisions have been made, according to the 

 distribution and combination of these pores : — 



I. Cystideans with pore-rhombs. The pores are disposed in 

 rhomboidal figures, the one-half of which belongs to one plate, 

 the other to its contiguous neighbour. Every two pores of these 

 rhombs appear to be invariably united by canals or grooves, 

 which are visible either upon the outer or on the inner side of 

 the plates, in such a manner that the united pores belong to two 

 different adjacent plates. 



a. Pore-rhombs without external connexion of the pores. 

 Hemicosmites and Caryocrinus-, in Hemicosmites the combining 

 grooves are, according to Volborth, upon the inner surface of 

 the plates. 



b. In Echinospharites granatum,Wah\enh . [Caryocystites gra- 

 natum, v. B.), the pores are united by bands projecting exter- 

 nally, which contain the connecting canal of the pores, and this 

 canal is always a single one between each pair of pores, or even 

 a series of pores*. The more importance is to be attached to this 

 circumstance, as the number of the calycine plates, even of the 

 basal plates in Caryocystites granatum, varies, so that some spe- 

 cimens possess more superimposed plates than others, and even 

 specimens with five basal plates are not rare. According to the 

 arrangement of the plates, I do not think that Caryocystites and 

 Echinosphcerites could be separated. 



A form nearly allied to Caryocystites granatum, observed by 

 M. Beyrich (Drift [Geschiehe'] near Berlin), the plates of whose 

 calyx are more numerous, is distinguished by the bands which 



* . . . und dieser Canal ist immer ein einziger zwischen je zwei Poren, 

 oder selbst einer Porenreihe. 



