116 TRANSACTIONS OF THE [maAR. 17, 
Ventral value about as wide as long; the front evenly 
rounded; back produced into a short pointed beak, angle of 
incidence of the two sides 110° to 120°. 
Sculpture of the posterior half of the valves, consisting of 
minute tubercles, sloping forward and arranged in rows, which 
arch forward across the mesian line from each lateral margin, 
giving the surface a cancellated appearance, like that of Lingula 
(?) favosa and Kutorgina pannula. Sculpture of the anterior ° 
part on the front and sides in the adult shell consisting of con- 
centric lines of growth, with faint, interrupted, radiating strie. 
One of the most interesting species among the early brachio- 
pods of the St. John group is the one named above. On account 
of its antiquity and because of its peculiar form in the embryonic 
stages, the writer now gives considerable space to the description 
of its characters. It is the oldest species of brachiopod belong- 
ing to the St. John group of which good material has been ob- 
tained, and the following extended account is based on this 
material. 
The ventral valve is evenly and moderately arched, except. 
that the sides are depressed toward the beak; the beak itself is 
prominent only toward the tip, and runs out horizontally from 
the middle of the valve. 
Interior of the Dorsal Valve (Figs. 1% to m).—The most 
noticeable feature of the interior of this valve is the three ridges 
which radiate from the hinge line toward the anterior end of the 
valve. The mesian ridge begins with a small tubercle near the 
umbo, is longer than the two lateral ridges, and divides into two 
outward arching forks; including these, it extends about two- 
fifths of the length of the valve from the hinge line ; its posterior 
part divides the pits of the hinge line where the posterior ad- 
ductor muscles were attached. The two lateral ridges extend 
forward from the two ends of the hinge line; and at the end of 
each, where it joins the hinge line, are situated the pits due to 
the attachment of the two branches of the cardinal muscle; out- 
side of these two ridges are a pair of elongated semilunar scars, 
where the posterior adjustor muscles were attached. There is 
a small lanceolate ridge flatter than those described, and broader, 
in front of the space between the forks of the mesian ridge; this 
divides the anterior adductor muscles.” 
Additional Note. In the centre of the valve are seven small 
scars grouped around a short mesian ridge (fig. 1 &); the scar in 
front of the ridge is oval, and may or may not have been pro- 
duced by a muscle; on each side of this scar extending diagon- 
ally backward and outward is a row of three scars of which the 
two first are round or nearly so, and evidently produced by 
