cbagin.] DESCRIPTIONS OF SPECIES. 59 
Occurrence. — One and a half miles east of Malone station. Be- 
sides the original example which the Messrs. Goodell discovered, and 
from which the illustration and measurements have been taken, 17 
other imperfect specimens and fragments were obtained at this 
locality, some of them indicating dimensions perhaps a fourth larger 
than those of the type. 
It will be seen from the description that the ornamentation of 
T. goodellii is variable. This, however, is true of most Trigonias, 
and not least so of those of the section, Undulatse, to which this species 
belongs. 
None of the Old World IJndulatse known to me corresponds very 
closely Avith T. goodellii. Several of those from the Great Oolite, 
which is so rich in Undulata?, bear more or less resemblance to it ; but 
the strict analogue, if found, may be expected to occur in the 
Tithonian. 
The species was named after the late Mr. Robert Wood Goodell, 
whose kind services in assisting me to determine the age of the Malone 
formation I have particularly acknowledged in my article on the 
r Discovery of marine Jurassic rocks in southwestern Texas," the 
paper in which the species was first briefly characterized and named. 
A Trigonia cast, showing nothing of the ornamentation, but indi- 
cating the general form of T . goodellii, having still larger dimensions 
Ithan any of the above, and belonging not improbably to this species, 
ijwas obtained by Doctor Stanton from conglomerate on the west face 
and near the top of Malone Mountain. It gives the following meas- 
urements : Height, 62 mm. ; length, 72 mm. ; breadth, -10 mm. 
Trigonia calderoni (C. and A.). 
PI. IX, figs. 4-6. 
Goniomya calderoni Castillo and Aguilera, 1895, Bol. Com. Geol. Mex., No. 
1, p. 9, PI. V, figs. 17, 18. 
Shell elongate-trapezoid, very inequilateral, moderately inflated, 
[the region of greatest convexity extending from the umbones down- 
ward and backward; anterior region relatively short and of consider- 
able height relative to the posterior, the anterior contour rounded: 
posterior region strongly produced backward and inclined a little 
lipward, gradually and strongly tapered toward its extremity, which 
|s obliquely truncate and looks backward and upward, its flanks more 
|pr less flattened ; base gently convex below the beaks, ascending thence 
teriorly in an easy convex curve and posteriorly slowly in a long 
nd nearly straight line; beaks but moderately elevated, their apices 
urved inward and somewhat backward and downward; escutcheon 
ather large and long, plain ; area of moderate width, flattened, trav- 
rsed lengthwise by a mesial groove, and transversely linear-plicate, 
HI 
