Fauna of the Morrow Group 
75 
by the closely related S, kentuckiensis. Two species of Hustedia, 
both new, are present in great abundance. The genus is spar- 
ingly represented in the Mississippian faunas but becomes of 
much greater numerical importance in the Pennsylvanian. As- 
sociated with it are a few individuals indistinguishable from 
Eumetria vera, a typical Chester form and a member of a genus 
which has not heretofore been known from the Pennsylvanian 
rocks of America. 
Athyrids are represented by seven species of Composita, some 
of which are present in great numbers. Only one of these, C. 
wasatchensis, is known to occur elsewhere although two others 
are closely related to common Carboniferous types. White's 
species was described from the Upper Carboniferous of Utah 
but it is similar to, if not identical with, a Madison limestone 
form to which Girty has applied the name C. humilis. 
Pelecypods form a considerable element in the Morrow fauna 
although they are not nearly so abundant as is generally the 
case among Pennsylvanian invertebrates. Ordinarily a species 
is represented in the collections at hand by less than a half 
dozen individuals while among the brachiopods there are scores 
of individuals of nearly every species. Solenomya, a genus about 
as abundant in the Mississippian as in the Pennsylvanian, is 
represented by a single species of doubtful affinity. Sphenotis 
halensis is a new species of this genus which like its near rela- 
tive, Sanguinolites , is with this exception confined, so far as 
reported in North America, to Mississippian rocks. Two species 
of Edmondia have been identified. One is referred with a query 
to a species which ranges in England, as reported by Hind, from 
the Lower Carboniferous into the Millstone Grits. The other, 
E. subtruncata, is characteristic of the Coal Measures of the 
Mississippi valley and has been identified from the Hermosa of 
Colorado. 
Nucula is represented by three forms, only one of which is 
known to occur elsewhere. N, parva is a typical Pennsylvanian 
pelecypod occurring in the Coal Measures of the Mississippi val- 
ley and with a considerable range, as it is known from the 
Mercer (Late Pottsville) of Ohio, the Ames and Brush Creek 
(Conemaugh) of Pennsylvania, and the Drum limestone (Stage 
D) of Kansas. Leda bellistriata has a similar distribution and 
