BRACHIOPODA. 
77 
edge, one on either side of the median line; a second, smaller pair, placed 
directly below the former; and outside of the latter a third pair of large elon¬ 
gate or subreniform impressions, converging forward. Beneath the rostrum 
there is a prominent spoon-shaped pit or chamber separating the above men¬ 
tioned impressions, with which the groove of the area is confluent. In the 
dorsal valve there are also three pairs of impressions disposed in nearly the 
same manner with those of the ventral valve. The dorsal valve is not known 
to possess an area. The surface is concentrically striated.” 
From the specimens before us, the shell-substance of Elkania desiderata 
appears to be largely corneous and distinctly laminated. Several examples in 
which the external layer of the shell has been exfoliated are covered with 
conspicuous papillae which may indicate a punctate structure in the inner layers, 
a feature not hitherto noticed in Obolella or its immediate allies. We have 
not been able to discover the minute cardinal area mentioned by Ford, although 
this feature should have been retained on the specimens examined, if it was 
distinctly developed. On the contrary, there appears to be, just within the 
marginal apex of what is above considered as the ventral valve, a broad, 
subtriangular depression, into which the central “spoon-shaped” cavity merges. 
This central cavity, in five examples of the interior of this valve, has a more 
or less distinct development, its definition being sometimes obscured by the 
flattening of the shell. When best preserved, it shows two narrow furrows 
diverging from its anterior extremity, which continue a short distance and be¬ 
come abruptly extinct. These two furrows separate the anterior extremities 
of the broad lateral muscular scars, which are quite indistinctly limited, while 
the smaller impressions, termed by Ford the “centrals”, are faint, but dis¬ 
tinctly seen in favorable light. The two small grooves in the rostral portion 
of the shell, diverging from the beak, were regarded by Ford as constituting 
the “ cardinal ” scars. These are, however, very elongate, and pass from near 
the pedicle-groove outward, skirting the posterior portion of the lateral impres¬ 
sions, and appear to terminate in distinct, subcircular scars situated between the 
laterals and the lateral margins of the valve. Should this character prove of 
permanent value, it will be of significance as affording an analogy between 
Elkania, Obolus and the Trimerellids. 
