54 MALONE JURASSIC FORMATION OF TEXAS. [bull. 266. 
with which it forms an acute angle. Anal region obliquely truncate on its 
extremity, excavated or concave in the vicinity of the benks, limited by a well 
marked carina which traverses the shell from the beak down to the posterior 
extremity at its junction with the inferior border of the shell; the carina is 
quite acute near the beak and becomes more obtuse in proportion as it recede! 
from it; the umbonal region, thus circumscribed by the umbonal crest, forms 
a sort of corselet, quite marked and excavated. Middle region of the sbell 
convex and in the form of a triangle limited by the anal crest and the oilier 
less developed which separates it from the buccal region; the major convexity 
of the sbell is just adjoining the anal crest and near the beaks. Liganiontal 
area not very much excavated and of regular dimensions. Cardinal border 
straight, in some specimens nearly as long as the sbell, but in ethers much 
shorter; anterior border obliquely rounded; inferior border nearly straight and 
parallel to the cardinal border, joining by means of a curve with the posterior 
border, which is oblique, slightly curved, and in the \onng forms nearly par- 
allel to the anterior border. Surface of the sbell provided with concentric lines 
of growth which have suffered interruptions and constitute more or less prom- 
inent corrugal ions. 
Length, 60.62 mm. ; breadth with relation to the length, 0.58. 
Locality: Arroyo de Alamitos, on the Alamitos rancho, in the Sierra de 
Catorce. 
By breadth (" ancho ") in the above is meant the dorso-ventra] 
dimension culled height by some writers. The lateral breadth, called] 
thickness (" espesor ") in the " Fauna Fosil," is not stated. 
The massiveness of this shell, its ventricose form, its broad beaksj 
and the demarcation of the middle from the posterior umbonal slope 
by a cariniform angulation, are features which might seem to inde- 
cate that Cucnllma catorcensis should he referred to the Texan C.\ 
transpecosensis ; hut the very prominent and subterminal beaks, and 1 
<m> Par as the description indicates) the absence of a second, or inner, 
angulation on the posterior corselet and of raised radial lines on the 
anterior umbonal -lope in C. catorcensis, appears to sufficiently dis- 
tinguish the Latter as a valid species. 
CtJCULLiEA CASTILLOI sp. 11. 
PI. VI. tigs. 11, 12. 
Shell of moderate size in the genus, short-trapezoidal; ventrieosity 
of medium degree, greatest considerably above the middle; ante- 
rior side short, rounded; posterior side straight, obliquely truncate; 
base gently convex; the infero-posterior part of the shell someAvhatl 
pointed, owing to a prominent, rapidly rounded shoulder that runs 
from either beak to the junction of the ventral with the posterior 
border, separating the outer convex slope from the posterior slope, 
which latter is strongly and concavely depressed, being strongly 
inflected near the shoulder and turning outward again about midway 
of its extension toward the posterior border, to form a prominent 
