852 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
surrounds the visceral region, and which probably served as a sort of anchoring 
device. The visceral part of the shell is usually small and is separated from 
the frill by a deep and prominent groove. The posterior side of the frill is a 
steep wall extending in the direction of the pedicle valve and ending in a narrow 
ridge. The main part of the frill in the pedicle valve extends from this ridge. 
The visceral area of the brachial valve is surrounded by a sharp and narrow 
_ ridge which is elevated more or less strongly above the visceral region. The 
anterior slope of this ridge is steep and long and ends in a narrow groove. At 
the anterior end or bottom of this slope the main part of the frill extends forward 
and laterally. 
The interior details of this genus are not easily discerned from the material 
available. Each of the features recorded has been gleaned from study of many 
specimens. To date no good interiors have been found. The information on the 
cardinalia were derived from 2 fragments dissolved out of Lower Edinburg lime- 
stone. In spite of these difficulties most of the details have been learned. 
The interior of this genus is most like that of Murinella and shares with it the 
prominent dental plates and the more or less strong adductor ridges. The interior 
of the pedicle valve of Murinella is not provided with the prominent, elevated 
ridge around the visceral area seen in Limbimurina, but that is a deviation 
brought about by the elaborate frill. 
Limbimurina is not rare in parts of the Rodman formation in central Pennsyl- 
vania but is a rare shell in the lower part of the Edinburg formation. The occur- 
rence of this bizarre form in the Lower Edinburg and the high Chambersburg 
and Salona emphasizes again the continuity of these two faunas. In the Rodman 
of central Pennsylvania Limbimurina is most often found in coarse calcarenites. 
It is not possible to be sure if this was the actual environment of this peculiar 
brachiopod or if the shells only represent debris washed into a sand bank. The 
shells in the calcarenite are usually single valves only and thus may have been 
banked up with the lime sand and broken bryozoans as a part of the bottom 
debris. 
The occurrence of Limbimurina shells in the Edinburg formation is not unlike 
that in the Rodman formation. Here, too, the lithology is either calcarenite or 
shell breccia, and most of the specimens are taken as single valves. The environ- 
ment is one of agitated water and if it was the locale for these shells, the ex- 
panded frills would have been of advantage in keeping the shells from being 
tipped over, particularly if steadied by a pedicle. 
LIMBIMURINA BREVILIMBATA Cooper, new species 
Plate 173, G, figures 32-34; plate 222, E, figures 6-9; plate 223, B, figure 4 
Shell large, attaining a width of 0.6 inch; transversely subrectangular in out- 
line ; hinge forming widest part ; sides oblique ; anterior margin broadly rounded ; 
surface marked by strong costellae separating groups of fine costellae beautifully 
cancellated by concentric lines; as many as 6 fine costellae constituting a group. 
Wrinkles irregular and variable but those along the posterior margin strong and 
fairly regular. 
