NIAGARA GROUP. 
199 
Genus LECANOCRINUS (nov. gen.). 
[Gr. Xsxavyj, pelvis, and xpivov, lilium ; from the bowlshaped form of the calyx in the typical species.] 
Pelvis composed of three plates ; second series consisting of five, with an intercalated plate ; 
third series, or scapular plates broad, with an interscapular plate in the same range ; arms with 
two joints, above which are several subdivisions closely arranged, the plates uniting laterally 
without interlocking. 
There are several species possessing characters sufficiently similar to admit of their union 
under a single genus ; regarding minutely only the more important parts of the structure, and 
recognizing a general similarity in habit and character of other portions of the animal. 
590. 1. LECANOCRINUS MACROPETALUS (n. sp.). 
Pl. XLV. Fig. 1 a - ft. 
Body sub-globose; pelvis composed of three small plates, succeeded by five costal plates of 
very large dimensions, two of these are pentagonal, one regularly hexagonal, and two hepta- 
gonal; a single sub-quadrangular intercostal plate ; scapular plates five, two of them pentagonal, 
and three with a short sixth side ; a single interscapular plate ; arm-plates two, above which 
the plates subdivide, a second subdivision occurring above the third or fourth plate from the 
first division ; extremities of the fingers folded inward, leaving an open cavity at the summit; 
column round, composed of smooth, alternately thicker and thinner joints which articulate 
strongly upon their outer margins ; canal rounded, with sometimes indications of a tripetalous 
form. 
This species is easily recognized by its general form, and particularly by the structure of the 
calyx, which is constant in all the specimens examined. The plates, to the subdivisions of the 
arms, are remarkably large, and the wide scapular plates give great width to this part of the 
body. The column is comparatively slender, and composed of smooth thick joints, alternating 
at irregular intervals with thinner ones. The edges of the joints of the column appear slightly 
rounded, giving it a characteristic appearance. 
There is a very interesting analogy between this species and the Ichthyocrinus Icevis; which 
is the more remarkable, since the latter belongs to the division with five pelvic plates. The 
Lecanocrinus seems, as it were, to be a farther development of the type first appearing in 
the Ichthyocrinus. It has been shown, that at the base of the latter, and entirely covered by 
the upper extremity of the column, are three minute plates, which nowhere reach the margin. 
The five small pelvic plates do not entirely surround the margin, but allow a , narrow portion 
of one of the second series to rest upon the edge of the column. If we suppose for one moment 
these three minute plates to be more fully developed, we have the pelvis of the Lecanocrinus. 
Regarding still farther those portions of the triangular pelvic plates of the Ichthyocrinus, inter¬ 
vening between the outer margin of those plates and the three minute plates of the centre, to 
