E. Billings on the structure of Crinoidea, etc. 69 
Art. VIII —WNotes on the structure of the Crinoidea, Cystidea 
and Blastoidea; by E. Bituines, F.G.8., Paleontologist of 
the Geological Survey of Canada.* 
1. Position of the mouth in relation to the ambulacral system. 
Tue earlier Paleontologists, Gyllenhal, Wahlenberg, Pander, 
Hisinger and others, described the lar ge lateral aperture in the 
Cystidea as the mouth, apparently on account of its resem- 
blance 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 ambulacral 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 Paleontology of New York, and by most others who have 
_ described these fossils, including myself, in my first paper on 
_ the Cystidea of Canada, published i 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 fate 
aperture was the mouth, in those species which were provide 
with a oe anus ; and that in all others it was both mouth 
tidean does not stand in the center of the radial system, as it 
does in all the existing Echinodermata. On — point Prof. 
Wyville Thompson has the following observati 
**T can see no probability whatever in the sonieh lately ad- 
vocated by Mr. Billings, and which has received some vague 
support from the writings of De Koninck and others, that the 
“pyramid” in the Cystideans i is the mouth, and that the aper- 
ture whence the ambulacra radiate is simply an “ ambulacral 
orifice.” Such an idea appears to me to be contrary to every 
analogy in the class. There can be no doubt of the existence 
of distinct openings for the passage of the ambulacral nerves 
* This paper was ade ye for the press last December, but, as my collection ses 
aad Blastoidea 7s ll, I thought it best to delay pu blication until I eould e 
e a greater n bavose < specimens. In Jan “me I Sin ie to 8. 8. Lyon, Tea, 
of Jeffersonville, epee and he repli ed that, if I would let him know what 
points I wished to invastignts, he would supply. me with the materi m my 
giving him the desired information, he, in the most liberal manner, sent me a large 
collection—much larger than I expecte “ receive—consisting of numerous speci- 
mens of several genera, many 2 them in the state of preservation best ada 
for nee eS tae of them ae, pet others silicified in a matrix 0! 
¢ KE. J. Chapman (Prof. 9 f Geology and Mineralogy, Univ Colt. "To. 
ronto) aka | kindly supplied me with several Russian Cystideans. To both of these 
gentlemen I here tender my thanks. 
B 
