18 DE, P. H. CAKPENTER ON" CEETAIN POINTS 



mouth aud the former the ambulacral opening, though he never 

 explains the meaning of this term. His descriptions of Agela- 

 crinus and Apiocystis contain no reference to the mouth at all j 

 but the lateral valvular opening, which is called the mouth in 

 Glyptocystis, is noticed as ovarian in Apiocystis, and as ovarian or 

 anal in Agelacrinus, while in the case of Garyocrinus it is spoken 

 of as " the mouth or anal orifice " *. !From Miller's descriptions 

 of Gallocystis, Hemicosmites, and SpJicsrocystis, it may perhaps be 

 inferred by a " scientist " that he believes the mouth of these 

 types to be situated at the ambulacral centre. But the average 

 amateur or student, for whom the book is also published, could 

 hardly be expected to discover this fact from such statements as 

 " oral, ovarian, and anal apertures," or " mouth apical ; opening 

 subapical; ovarian opening on the summit "t. 



No educated palseontologist would now admit the possibility 

 of such extraordinary departures from the general type of Echi- 

 noderra structure as Miller's descriptions involve; and few, if 

 any, will now deny that the position of the mouth of a Cystid 

 coincides with that of the ambulacral centre, as was so ably 

 argued by the late Sir AVyville Thomson | in 1861, and subse- 

 quently by Llitken § and A. Agassiz ||. In some genei-a there is 

 evidence of its having been concealed beneath a covering of oral 

 plates, as in so many Palgeocrinoids. These are well preserved 

 in GyatJiocysfis Plautince, Schmidt ^, and are tolerably equal in 

 size, as in StepJianocrinus. But in various species of SphoEronis as 

 figured by Angelin, in GlyptosplicEra LeucMenlergi (PI. I. fig. 15), 

 and in Pyrocystis desiderata, Barrande (PI. I. fig. 11), the 

 posterior oral is larger than its fellows, as in Haplocrinus and in 

 so many Camerata**. 



* Op. cif. p. 231. t Ibid. pp. 230, 282. 



\ " On a new Palajozoic Group of Ecbinodermata," Edinburgh New Pbilo- 

 sophical Journal, 1861, vol. xiii. p. 112. 



§ " Endnu et Par Ord om de gamle Soliliers ' Snabel ' og Muud," Vid. Med. 

 Naturbisk. Forening i EjobenbaTU for 1869, Nr. 9-13, pp. 185-188. 



II " Note on Loven's Article on Leskia mirabilis, Gray," Auuals Lye. Nat. 

 Hist. 1869, vol. ix. pp. 242-245. 



^ " Ueber CyathocystiH PlavMna, eineueue Oystideenf'orm aus Eeval," Verb, 

 russ. kais. miu. Gesellscb. St. Petersburg, 1880, ser. 2, yoI. xv. pp. 1-7. 



** I take this opportunity of cordially acknowledging the generous manner 

 in which Messrs. Wacbsmuth and Springer have recently admitted the truth of 

 the view which I have advocated persistently since 1879, respecting the homology 

 of the four anterior proximals of the Palteocrinoidea with the orals of the 

 Neocrinoidea. They were steadily opposed to it from the first, but have at last 

 assented to it (Proc. Acad. Nat. Sci. Pbilad. 1888, p. 348) ; and now that they 



