BEACHIOPODA. 865 
entire structure does not extend beyond the middle of the shell. 
The ascending lamelle are very fragile and usually destroyed in 
fossilization. 
Type, Dielasma elongatum, Schlotheim (sp.). 
Distribution. Devonian (-?)) — Permian. 
Subgenus Cranzna, Hall. 1893. 
(Plate 53, figs. 4-9.) 
Biconvex shells having the hinge-plate constructed as in 
CrypP ONELLA and not adherent to the bottom of the valve as in 
Dietasma; the crura also arise normally from 
the lateral divisions of this plate. Form of the 
brachidium as in Drenasma, its descending iS 
branches being highly divergent, the ascend- 
ing branches abruptly recurved, making a 
broad, gentle curvature above; at the same 
time this recurved band is so very fragile as to See eae 
be almost invariably destroyed. The entire Romingeri, Hall,(sp.. 
length of the loop, as in Drgrasma, and in ar he arertitons be 
contradistinction to CryproneLtta and EUNELLA, prachidium and the 
is about one-third thit of the brachial valve. HU SaSs 
(Type, Cranena Romingeri, Hall (sp.). Devonian.) 
Dielasmina, Waagen. 1882. 
Plicated shells which possess more or less of the characters of 
Drmuasma. They have the dental plates of the pedicle-valve and 
Fie. 503. Fia. 504. 
Dielasmina plicata, Waagen. 
Dorsal and front views. CWAAGEN.) 
the general form of the brachidium in that genus, as far as 
the interior is now known. i 
Type, Dielasmina plicata, Waagen. 
Distribution. Carboniferous. 
109 7 
