1869.] BILLINGS — STRUCTURE OP CRINOIDS, ETC. 277 



NOTES ON THE STRUCTURE OF THE CRINOIDA, 

 CYSTIDEA AND BLASTOIDEA. 



By B. Billings, F.G.S., Palaeontologist of the Geological Survey 

 of Canada.* 



1. Position op the mouth in relation to the 

 ambulacral system. 



The earlier Paleontologists, Gyllenhal, Wahlenberg, Pander, 

 Hisinger, and others, described the large lateral aperture in the 

 Cystidea as the mouth, apparently on account of its resemblance 

 to the five-jawed oral apparatus of the sea-urchins. In his 

 famous Monograph " Uber Cystideen," 1845, Leopold von Buch 

 advocated the view, that it was not the mouth but an ovarian 

 aperture; and that the smaller orifice usually situated in the apex, 

 from which the ambulaeral grooves radiate, was the true oral 

 orifice. These opinions were adopted by Prof. E. Forbes, in his 

 Memoir on the British Cystidea, by Prof J. Hall, in the Paleon- 

 tology of New York, and by most others who have described these 

 fossils, including myself, in my first paper on the Cystidea of 

 (^anada, published in the Canadian Journal in 1854. In 1858 

 I re-investigated the subject while preparing my Decade No. 3, 

 and came to the conclusions that the lateral aperture was the 

 mouth, in those species which were provided with a separate 

 anus ; and in all others it was both mouth and anus. The small 

 apical orifice I described as an ambulaeral aperture. According 

 to these views, the mouth of a Cystidean does not stand in the 



* This paper was prepared for the press last December, but, as my 

 collection of the Blastuidea was small, I thonght it best to delay pub. 

 lication until I could examine a greater number of specimens. In 

 January I applied to S. S. Lyon, Esq., of JeflFersonville, Indiana, and he 

 replied that, if 1 would let him know what points I wished to investi- 

 gate, he would supply me with the materials. On my giving him the 

 desired information, he, in the most liberal manner, sent me a large col- 

 lection—much larger than I expected to receive— consisting of numerous 

 specimens of several genera, many of them in the state of preservation 

 best adapted for investigation— some of them empty and others silicified 

 in a matrix of limestone. Prof. E. J. Chapman (Prof of Geology and 

 Mineralogy, Univ. Coll., Toronto) also kindly supplied me with several 

 Russian Cystideans. To both of these gentlemen I here tender my 

 thanks. 



