558 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
to have come from the Sinuites bed at the base of the Martinsburg shale, 1 mile 
south of St. Thomas, Pa. Although this specimen is a badly exfoliated interior 
filling and an immature specimen, it is nevertheless selected as lectotype. No 
other choice is possible because the remaining three specimens are all of dubious 
value. 
The specimens illustrated by figures 12 and 13 on plate 49 are very poorly 
preserved and are evidently derived from a shaly matrix. The specimen shown 
in figure 12 is a fragment of a brachial valve showing the umbonal part and the 
brachiophores but not preserving the cardinal process. The figure is approxi- 
mately natural size. The specimen illustrated by figure 13 is a complete speci- 
men but is badly crushed. The illustration is approximately x2. These two 
specimens bear the catalogue number 66174. The label accompanying them 
reads: “Trenton (bed VII of section), Strasburg, Va.” This bed according to 
Ulrich’s notes corresponds to the lower Edinburg (Cyrtonotella zone) of Cooper 
and Cooper. Thus these specimens have nothing to do with the lectotype which 
occurs hundreds of feet higher. These specimens are assigned somewhat doubt- 
fully to O. multicostellata which is identified in the Cyrtonotella beds in the 
vicinity of Strasburg. 
The third cotype under number 66174 is another immature but complete speci- 
men which is the best preserved one of both lots. It could not, however, be se- 
lected as the lectotype because its horizon and locality are equivocal even though 
it appears under the above number. This specimen is dark gray, lustrous, and 
gives the appearance of having come from the higher beds of St. Thomas or even 
of Strasburg. It resembles numerous specimens of the Oranda formation from 
Virginia more than it does those from the shaly beds of the lower Edinburg 
formation. This equivocal specimen is here referred to O. simulatrix, but its 
stratigraphic horizon is uncertain. 
With reference again to the lectotype, it must be stated that the specimen is 
immature. The figure and its legend given by Bassler give no indication of the 
enlargement of the figure. The figure is actually approximately x2. The speci- 
men is quite unlike the figure, which is retouched to such an extent that it is 
difficult to identify the specimen with it. The figure shows prominent costellae, 
and the sulcus occupied by 2 long and 2 short costellae. These give an entirely 
erroneous idea of the species because the lectotype is so exfoliated that only the 
stronger parts of the ornamentation are exhibited. 
Confidence is here expressed that the lectotype is the young of the common 
O-xoplecia of the Oranda formation; therefore the name simulatrix is used for 
it. The above description is based on adult material from many localities and 
is thought to represent the species more accurately. 
As defined herein O. simulatrix resembles some of the larger species found in 
the Appalachians. It is suggestive of O. multicostellata but differs importantly in 
its stronger ornamentation and profiles. Its differences from O. nevadensis are 
also in exterior details of ornamentation, fold and sulcus, and outline and pro- 
files. It differs from O. pennsylvanica, which is approximately contemporaneous, 
in its less strong costellae and its more robust profiles. 
