119 Morgan Expeditions. 
Moderately abundant in the Devonian sandstone of Ereré, 
Prov. of Para, Brazil; associated with Nuculites Nyssa, 
Spirifera Pedroana, ete. 
Named after M. Léon Gillet, Prof. Hartt’s able and oblig- 
ing agent at Para. | 
LAMELLIBRANCHIATA. 
Genus NUCULITES, Conrad. 
Nuculites Nyssa. 
Nuculites Nyssa, Hall. Lamell. Shells of the U. Held., Ham. and Chem. 
Groups, etc., 1869. (Preparatory for the Paleontology of N. Y.) 
Description of Ereré specimens :—Shell of medium size, longitudinally 
sub-ovate or sub-triangular in outline, and of moderate convexity. Ante- 
rior margin well rounded and narrower than the posterior. The dorsal 
margin, curving slightly, extends obliquely backwards from the beak to 
the posterior extremity of the shell, a short distance above the termina- 
tion of the median antero-posterior diameter. The ventral margin is mod- 
erately rounded and, together with the anterior and posterior margins, 
forms an elliptical curve. Beaks about one-fourth the length from the 
anterior extremity, with the apices acute and strongly incurved to the 
hinge line. Valves most convex at a point just above and anterior to the 
middle. The surface arches rapidly and more or less regularly from 
the ventral margin to the beak, but is generally a little more strongly 
curved in the umbonal region, and is broadly flattened, rounding suddenly 
to the dorsal margin. The slope toward the posterior margin is convex 
and more abrupt than toward the ventral margin; toward the anterior 
margin it is still more abrupt, becoming gradually concave near the beaks. 
The septum, curving very slightly, and with its concave side forward, 
extends down nearly two-thirds the shell height, cutting the antero-poste- 
rior diameter at about one-fourth its length from the front. Surface 
smooth or marked with a few indistinct lines of growth. Length, 24 ™™; 
height, 17 ™™; depth of single valve,5™™. Specimens of larger size are 
numerous. 
This species of Nuculites, which is the most common 
lamellibranch at Ereré, proves to be identical with V. Vyssa 
of Hall, found in the Hamilton group, New York. 
We are indebted to Prof. Hall for the identification of the 
forms from the two places. 
