188 P. HERBERT CARPENTER. 



appeared to regard as a central ambulacral orifice, and con- 

 sequently supposed that on Schultze's theory, " Caryocrinus 

 ornatus was a polystome animal, and drew in its food through 

 its six ovarian apertures." To me, as it did to Billings,^ 

 this certainly does appear " utterly incredible." 



Wyville Thomson," Agassiz,^ and Liifken have laid great 

 stress on the fact that in all the recent Echinoderms the 

 mouth is in the centre of the radial system, and that, there- 

 fore, the valvular orifice of the Palceocrinoidea, which is 

 situated at the point in the vault behind the radial centre of 

 the ambulacra, cannot possibly be the mouth, but is probably 

 the anus. 



Billings admitted the universal connection of the mouth 

 and radial centre in the recent Echinoderms, but, being 

 firmly convinced that the valvular orifice was oro-anal in 

 function, he asserted^ that " in at least a large proportion of 

 the palseozoic Crinoids the mouth was altogether discon- 

 nected from the radial system," this being evident from 

 "simple inspection." He did not, however, make it clear 

 how " simple inspection^' can demonstrate the oral nature of 

 the valvular orifice. He supposed the same to have been 

 the case in the Cystids, in Avhich, like De Koninck^ and 

 Gray,^ he regarded the " ovarian pyramid" of Von Buch as 

 oral in function ; while the small opening near the centre of 

 the upper part of the body, from which the ambulacra radiate, 

 was called by him an ambulacral orifice,'^ through which 

 " the vessels of the aquiferous system and of the organs of 

 reproduction which were situated in the grooves of the arms 

 communicated with the interior." Loven^ has entirely adopted 

 Billings' views, but Agassiz, like Liitken and Wyville Thom- 

 son, has opposed them strongly, and reaffirms the views of 

 Volborth and Miiller, that the mouth is at the radial centre 

 of the ambulacra, and is, in fact, the minute ambulacral 

 orifice of Billings. 



It appears to me that there can be no doubt about this so 



1 ' Canadian Naturalist/ 1870, p. 197. 



- "On a New Palaeozoic Group of Echinodertnata," 'Edinburgh New 

 Philosophical Journal/ vol. xiii, p. 106. 



3 " Note on Loven's Article on Leskia mirahilis," ' Annals of the Ly- 

 ceum of Natural History/ vol. ix, pp. 243 — 245. 



* ' Canadian Naturalist/ 1869, p. 279. 



^ Loc. cit., pp. 53 et. seq. 



« ' Catalogue of the Recent Echinidse or Sea Eggs in the Collection of 

 the British Museum/ 1855, p. 63, t. 4, f. 4. 



'' Decade iii, p. 15. 



^ "Oni Leskia mirahilis" Gray, ' Ofversigt af Kongl. Yeteuskaps- 

 akademiens Eorhandlingar/ 1867, No. 5, pp. 43'6— 440. 



