1040 DR. J, W. GREGORY ON THE CLASSIFICATION _‘[ Dee. 15, 
Bohm has founded the genus Ophiopege on the type species of 
Aganaster [2 a. p. 159}. 
The genus Cholaster of Worthen and Miller [19. pp. 328-329, 
pl. xxxi. fig. 4] appears to be allied to Aganaster, but the structure 
of the ambulacral ossicles is unknown. 
Family 4. ONYOCHASTURIDS. 
Diagnosis.—Streptophiure with well-developed vertebral ossicles, 
and with very flexible, contorted, unbranched arms; there are no 
external arm-plates, the integument containing granules only. 
Distribution.—Keokuk and Burlington Stages, Lower Carboni- 
ferous, Iowa and Llinois. 
Genus Onycuastur, Meek & Worth. 
Type species.—Onychaster flewilis, Meek & Worth. [Proc. Acad. 
Nat. Sci. Phil. 1869, p. 83; 11. pp. 526-528; 11a. p. 510, pl. xvi. 
fig. 3]. 
Sepia oailhi interesting genus has hitherto been placed 
among the Huryalide, of which it has been regarded as the best 
known fossil representative. As Prof. Bell, however, has re- 
marked, Meek and Worthen’s clear figures of the vertebral ossicles 
show that the articular surfaces are Streptospondyline and not 
Cladiophiuroid. 
Family 5. HUCLADIIDS. 
Diagnosis. —Streptophiure with contorted branching arms. 
There are five pairs of large plates (? radial shields) on the abacti- 
nal side. The madreporite is large and dorsal in position. The 
arms have no external arm-plates, but are covered by a granular 
integument. Ambulacral ossicles primitively Streptospondyline. 
Genus Evctapi1a, H. Woodward, 1869 [18]. 
Type species.—Eucladia johnsoni, H. Woodward, Lower Ludlow, 
near Dudley. 
Remarks.—The affinities of this magnificent Starfish have been 
left in some doubt owing to the absence of information as to the 
structure of the vertebral ossicles. It has generally been assigned 
to the Euryalid, owing to its granular integument and branching 
contorted arms. Fortunately, however, I have found the articular 
surface of the vertebral ossicles exposed on the side of the block 
of limestone containing the specimen. The articulation is truly 
Streptospondyline of a rather primitive type (fig. 6a, b, p. 1041). 
The ossicle is egg-shaped in section, with the broader end above. 
Two broad muscle-fields occur, one at each of the quadrants of 
the ossicle. On the central line just above these there is a small 
knob. The upper half of the ossicle is occupied by two pairs of 
depressions separated by simple ridges. 
