248 
PALAEONTOLOGY OF NEW-YORK. 
Fig. 21. The lower side of the specimen, of the natural size. 
Fig. 22. One of the arms enlarged. 
Fig. 23. Several of the ossicula, with the short spines as they appear bordering the avenue. 
Position and locality. In the shale at Lockport. ( Collection of Col. Jewett.) 
The principal genera of Cystideee, which have been described, are given in the table on a 
preceding page. Two other genera are added in the preceding descriptions, and one which is 
not positively ascertained, under Crinoidese. To these we have to add another form in the 
Penlamerus galeatus limestone ; above which, we have, yet, no well ascertained species of 
this family. It is not improbable, however, that we shall meet with species when more com¬ 
plete examinations are made in the higher rocks. It is not a little interesting to observe that the 
development of species in this family corresponds to the Crinoideae ; both being more numerous 
in the Niagara period, than in any preceding or succeeding period of the New-York strata. 
Since the preceding pages were in type, a farther examination of a specimen of the Callo- 
cystites, which was coated with hard shaly matter, has revealed the fingers or tentacula at¬ 
tached to the fragment of an arm still remaining. This has been figured on Plate 50, and 
completes the characters of this beautiful fossil. In the same figure, is shown more distinctly 
the longitudinal division between the bases of the arms upon the summit. 
Further examinations among specimens of Cab.yocr.inus have served to convince me that 
the orifice termed the mouth is not the only one existing upon the summit; and I am more 
inclined to regard the so called mouth as an ovarian aperture, corresponding to the organ of 
similar structure in the Cystidese. In the description of this fossil, the mouth was regarded as 
being in the centre of the base of the triangle formed by the summit. No sufficient reason has 
been shown why this part assumes a triangular form, which is almost always apparent in 
well preserved specimens ; but we have an explanation of the reason why the side on which 
the mouth is placed assumes a more direct line, from the wider space between the arms at that 
point. Now if we regard the mouth as posterior, we shall find on the left side, near the middle 
of one side of the triangle, an aperture or pore, which in some instances appears to be closed 
by small plates. In no instance where it has been sought for, in this position, have we failed 
to find some evidence of its existence. It has been impossible to pursue the examinations far 
enough to decide the nature of this organ, or whether it be simple or two organs. 
I w T as led to search for an aperture in this position from the fact that the mouth and anal 
pore in the Callocystites and Apiocystites are always on the left side of the summit, 
regarding the ovarian aperture as posteal; and this aperture in Caryocrinus, be'ars the same 
relation to the mouth or ovarian aperture. 
On the opposite or right side of the body of Caryocrinus, there is, in several specimens, 
some appearance of an aperture or tuberculous plate, which has not been sufficiently examined. 
These facts induce me to believe that there is a very close affinity between this genus and some 
of the cystidean genera. 
