BRAOHIOPODA. 861 
oval as in many species of Drmtasma ; the inverted pedicle-sheath 
or collar is slightly developed within the aperture. The teeth 
are strong and supported by dental lamellz which divide the 
umbonal cavity into three chambers ; near the apex they join the 
somewhat thickened scar of the pedicle-muscle, and extend 
beyond its anterior margin with a slight convergence, always 
resting on the bottom of the valve. The pedicle-emuscle makes 
the strongest scar of all the muscular bands, the adductors being 
narrow and central, and the diductors scarcely delimited. 
In the brachial valve the hinge-plate is large, elongate and 
concave; it is divided by two low ridges diverging from the 
apex, and from these the plate rises toward the 
sides into decidedly elevated socket-walls; between 
the diverging ridges the surface is rather deeply 
depressed, and, toward the apex, is perforated by 
a circular foramen. The crura are slender, very 
short, curving inward and upward, making two 
long and narrow crural apophyses. The descend- 
ing lamelle are carried forward, following the Aue 
curves of the valves for nearly two-thirds the wre 495. cryp- 
length of the shell, and abruptly reflected ; the as- fe Mera tk 
cending lamelle returning to within a short dis- ie ar ne 
tance of the crural apophyses. The whole struc- Seine 
ture is very similar to the brachidium of the adult living Macx- 
LANIA (W ALDHEIMIA). 
The adductor scars are more or less distinct, the anterior mem- 
bers being the more clearly defined. These scars are usually 
represented only by three straight lines diverging from the 
umbonal region. Vascular sinuses originate about the muscular 
areas of both valves and are directed forward with frequent 
ramifications. 
The shell-structure is highly punctate. 
Type. Cryptonella rectirostra, Hall. 
Distribution. Devonian — Lower Carboniferous. 
Subgenus Eunella, Hall. 1893. 
(Plate 52, figs. 24-28.) 
Shells exteriorly like CrypronELya. 
The brachidium, compared with that of Crypronetra, is quite 
short, extending less than one-half the length of the brachial 
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