BRACmOPODA. 137 



nal septa, it agrees throughout with Anoplotheca and Ccelospiea. In the 

 original diagnosis of Leptoccelia, L. Jiabellites was described and figured as pos- 

 sessing a terebratuloid loop. It was, however, distinctly stated that the evi- 

 dence of this structure was confined to a single specimen containing cavities in 

 its filling of quartz, which corresponded to the restoration given. Subsequent 

 investigations have not corroborated this observation. 



The specimens of this species are not favorably preserved for the retention 

 of the brachial apparatus, those from Cumberland, Maryland, being replaced 

 by silica and often filled with coarsely crystallized quartz, while those from 

 New York, Gaspe and the South American localities are usually in the form 

 of casts in an arenaceous sediment. Later observations have not shown any 

 trace of the organ described, and it is highly improbable that a species agreeing 

 in all known points of structure with the spirigerous groups just discussed, and 

 having also a fibrous shell structure, should possess a terebratuloid loop. Ref- 

 erence has been made to the fact that in Calospira concava the stout umbonal 

 blades of the primary lamellae and the loop are frequently all that is retained 

 of the brachial apparatus, the rest of the brachidium being very delicate ; 

 the parts thus retained are by themselves certainly suggestive of terebratuloid 

 structure, and not unlike the loop ascribed to L. flabellites. With our present 

 knowledge it would be unwise to separate Leptoccelia too widely from 

 Anoplotheca and C(elospiba. 



There are but two other species which can safely be referred to the group 

 of L. flabellites, namely, L. dichotoma and L. fimbriata, Hall, also  from the 

 Oriskany fauna at Cumberland. The latter shell possesses a peculiarity in the 

 extension, from between the cardinal extremities of the valves, of the inner 

 lamina of the shell substance in the form of a row of spinules having the 

 appearance of matted cilia. (See Plate LIII, figs. 47, 50.) 



Leptocalia flabellites, the type species, is remarkable for its wide distribution. 

 Like Tropidoleptus carinatus and Vitulina pustulosa, it abounds in the lower 

 Devonian strata of South America. Morris and Sharpe described the species 

 under the name Atrypa palmata, from material collected by Darwin in the 

 Falkland Islands ; Salter described it as Orthis Aymara, from various localities 



