PLATE IV e—C ontinued. 
Orbiculoidea Randallt. Hall. 
Pig-. 18. The exterior of a pedicle-valve; showing, from compression,, the apical muscular ridge, the 
radiating.pallial sinuses, and the internal ti-ack of, the pedicle-furrow extending toward the 
margin and interrupting--,the concentric growth-lines. The overlapping marginal portion of the 
opposite valve is seen about the posterior arc of the circumference. Natural size. 
Hamilton group. Near Schoharie, N. Y. 
- Obiculoidea ,'pulchra, sp. nov. 
Pig. 19. The exterior of a pedicle-valve. X 1.5. 
,jCuyahoga shale. r Berea, Ohio, .. m 
Orbiculoidea Manhattanensis, Meek and Hayden. 
Fig. 20. The interior of a pedicle-valve ; showing the character of the'pedicle-area, the 1 radiating Vascular 
lines, and where the shell is broken On the anterior portion, the Character of the external 
ornamentation and the unusual thickness of the valve. 
Coal Measures.'. ' R:d.mj_ co\inty, Kansas. 
QEHLERTELLA, 1 sI-gen. nov. 
Page 120. ’ 1 
CEhlertella pleurites. Meek. 
Fig. 21. The interior of a pedicle-valve ; showing-the elevated pedicle-ridge and the open, marginal fora¬ 
men. Natural size. 
Fig. 22. Profile of the same, giving the internal elevation of the pedicle-area. 
Figs. 28, 24. Brachial valves, differing slightly in outline, and showing the posterior position of the apex. 
Waverly group. Newark, Ohio. 
LINDSTRCEMELEA, s.-gen. nov. , 
. Page 12ol 
LiNDSTRCEMELLA ASPID1UM, Sp. 110V. 
Fig. 25. A brachial valve, from which the shell is largely exfoliated, but retaining sufficient to show the dis¬ 
tinct, elevated, concentric ridges characterizing the external surface. ; The great lateral ridges 
and the fainter median septum are.represented by furrows. At the posterior extremities of the 
former are seen two small subcircular muscular impressions, while the scars of the anterior 
adductors are strongly developed. Natural size. 
Fig. 26. The counterpart of the same; drawn from a g-utta-percha impression; showing all the internal 
characters in their natural relief. 
Hamilton group. Near Hamilton, N. Y. 
Fig, 27. A natural cast of the exterior of a large/pedicle-valve believed to belong to this species; showing 
the character of the surface ornamentation, and the peculiar undulation of the concentric ridg-es 
on approaching the pedicle -area. The pedicle-passagei differs from that in the normal mature 
Orbiculoidea, in not being closed, though its margins appear to be in contact. The characters 
of this area as represented in the drawing, have been slightly restored from other specimens. 
Hamilton group. Near Leonardsville, N. Y. 
Fig. 28. A small pedicle-valve, with the characteristic ornamentation and strongly developed foraminal 
groove. . i. ■ , , , .| { r / 
Hamilton group. Near Bcirieh, N. Y. 
RCEMERELLA, s.-Oen. nov. 
Page 120. 
Rcemerella grandis, Viinuxem. 
Fig. 29. The exterior of a brachial valve. 
Hamilton limestone. Falls of the Ohio. 
Fig 80. The interior of a pedicle-valve from which the shell has been partially exfoliated, exposing the 
matrix and the cast of the external pedicle-groove. 
Fig. 31. The counterpart of the same specimen, from a gutta-percha cast; showing all the essential ex¬ 
ternal characters. The extreme depression of the anterior portion of the valve and the cor¬ 
respondingly great elevation of the pedicle-area are features subject to some slight variation 
within the limits of the species. 
Hamilton group. Cazenovia, N. Y. 
