NIAGARA GROUP. 
215 
600. 2. STEPHANOCRINUS GEMMIFORMIS (». sp.). 
Pl. XL VIII. Fig. 2 a -i. 
Column round, composed of joints of equal thickness ; canal round, minute, articulating 
surfaces of joints minutely crenulated or denticulated near the outer margin ; body triangular 
at base, rapidly enlarging above, and becoming rotund in the middle and slightly contracted 
near the summit; structure as in the preceding; pelvic plates three, short, angular below, and 
becoming curved above ; costal plates five, succeeded by an equal number of plates forming 
the spiniform processes around the summit; upper margins of the costal plates scarcely de¬ 
pressed or excavated ; structure of the summit precisely as in the preceding species ; surface 
granular. 
This species is usually minute, the largest entire specimen seen being figured in 2 a, b. It 
is clearly distinct from the preceding, not only in size and form, but in surface markings. The 
plates have no carinee upon their surfaces ; and though the form is more sharply triangular at the 
base, it nevertheless expands rapidly, and becomes rotund above. At the base of the third 
range of plates, the fossil is slightly contracted ; which contrasts strongly with the preceding 
species, which has its greatest breadth at this point. The coronal processes are slightly con¬ 
verging, while in the other they are diverging. There is otherwise no appreciable difference in 
the structure. In one or two specimens, the structure of the crown has been distinctly observed. 
In all its parts there is the most perfect similarity of structure, with slight differences in the 
proportions. 
A single fragment has been found, where the base indicates that the entire individual was 
twice or thrice as large as the largest one figured. 
Fig. 2 a. An individual somewhat larger than the ordinary size. The position in which it is 
figured, shows the pentagonal pelvic plate, and the short sloping sides of the ad¬ 
joining plates. 
Fig. 2 b. A specimen with a few joints of the column attached. 
Fig. 2 c. The crown of an individual, as it is usually seen. 
Fig. 2 d, e. The base of one of these, and the same enlarged, showing the rapidly expanding 
form which becomes nearly round or very obtusely pentagonal at the centre. 
Fig. 2 f. The structure of this species as shown from fig. 2 a. 
Fig. 2 g. A small specimen, where the base is much drawn out, and quite triangular. 
Fig. 2 h. The same enlarged, showing more distinctly the form and proportions. 
Fig. 2 i. A portion of the surface enlarged, showing the character of the ornament. 
Position and locality. In the shale at Lockport. Usually found at the base of the cliff, 
washed out by the rains. ( state Collection.) 
