’ BRACHIOPODA. 837 
which converge and unite before reaching the bottom of the 
valve. Thus is formed a deep but short spondylium, which is 
supported, near its apical portion, by a median septum, but is 
free for fully one-half its length. 
In the brachial valve there are also two convergent plates 
bounding the deltidial cavity, larger and stronger than those of 
the opposite valve. These plates may rest upon the bottom of 
the valve, and, toward the posterior extremity, probably always 
do, but anteriorly they become free, forming a spondylium 
which is supported by a median septum extending beyond the 
anterior edge of the plate. Thus these two valves, which are 
very similar in exterior, the pedicle-valve being only slightly the 
more convex and with a low median sinus, are also closely alike 
on the interior, each being furnished with a spondylium. 
Type, Syntrophia lateralis, Whitfield (sp.). 
Distribution. Cambrian (?)— Lower Silurian. 
Camarophoria, King. 1846. 
(Plate 45, figs. 5, 6.) 
Subtrigonal, concavo-convex rhynchonelliform shells, with 
median fold and sinus well developed, and surface more or less 
strongly plicated. Beak sharp, incurved ; deltidial plates in an 
incipient condition, often wanting. 
In the pedicle-valve the dental plates converge, forming a 
moderately large spondylium which, in the umbonal region, rests 
upon the bottom of the valve, but anteriorly is supported by a 
vertical median septum. The spondylium is short, while the 
supporting septum is carried beyond it, sometimes to nearly one- 
half the length of the shell. Near the teeth, which are small, 
there are two accessory supporting lamellz abutting on one side 
against the outer surface of the converging dental plates, and on 
the other against the interior cardinal surface of the valve ; 
thus inclosing small lateral umbonal cavities. Muscular scars of 
this valve always obscure. 
In the brachial valve the cardinal plate is narrow, subtriangular, 
in the typical species bearing a very small cardinal process, 
which in other species is rarely present. The hinge-plate is 
traversed by two fine divergent ridges running outward from 
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