NIAGARA GROUP. 
239 
the second series is more numerous, and upon the upper angles of two of these the ovarian orifice 
rests, its upper half occupying a depression in the base of a plate of the third series. The 
upper pairs of pectinated apertures are likewise in part borne by two plates of the second series ; 
while the five arms, which may be simple or subdivided, radiate from the apex, covering much 
of the third and nearly all of the fourth series of plates. 
606. 1. CALLOCYSTITES JEWETTII (n. sp.). 
Pl. L. Figs. 1 -11 ; amU2-16 var.? 
General form of body oblong ovoid, nearly symmetrical ; base composed of four plates, 
one of which, bearing the pectinated aperture, is pentagonal, the second and fourth hexagonal, 
and the third heptagonal. These plates support on their upper edges eight plates in the second 
series, Nos. 5 and 6 of which are similar, and also 11 and 12, the others being of dissimilar form. 
Of the basal plates, No. 1 is not directly opposite to the ovarian aperture ; but the position 
of No. 6, bearing the second one of the lower pair of pectinated apertures, is almost directly 
opposite ; and a line drawn from this aperture, through’ the centre of the base, to the lower 
angle of plate No. 6, will divide the body into two parts of equal dimensions, though not 
composed of similar parts. In the third series of plates, a single one is excavated on its lower 
side, to form the upper margin of the ovarian aperture ; and two other plates bear the upper 
member of the higher pairs of pectinated apertures. Above the apex of the pentagonal basal 
plate, and resting upon the sloping edges of plates five and six in the second series, is a qua¬ 
drangular plate marked 14 (fig. 11), its two higher sloping sides flanked by 13 and 15. This 
is probably a supernumerary plate, not present in all individuals of the species. Every one of 
these plates is more or less covered by the arms, which spread over the surface. The pectinated 
apertures of the upper pairs are situated on each side of the ovarian aperture, and equidistant 
from it, but not on opposite sides of the body. The individuals of the pair on the right side 
are nearly horizontal in regard tp each other, while those of the other pair are one above the 
other, and the basal or anteal pair are nearly opposite the ovarian aperture. Arms double, or 
composed of two parallel series of plates separated by a sinuated groove ; plates of the arms 
of two forms, alternating ones similar, and opposite ones in the two series of different forms ; 
fingers or tentacles composed of minute plates, articulating with the arms at the higher junction 
of the larger and smaller joints and at the bottom of each sinus. Surface of the entire body 
ornamented by polygonal depressions, having a more or less perfectly defined border and a 
granulated surface. 
This is a most beautiful species, and, when furnished with tentacula and pedicel, was a 
magnificent form. The base is large, giving room for the strong attachment of a broad column ; 
and the lower series of plates are expanded, with the exception of the pentagonal one, which 
narrows this side, and gives to the whole body a more nearly straight anteal side, while the 
posteal or ovarian side is swollen or pressed outward. The plates forming the ovarian pyramid 
have not been observed ; but from the character of the aperture remaining, we may fairly infer 
