66 MALONE JURASSIC FORMATION OF TEXAS. [bull. L»6G. 
imbrications, or constrictions that tend to mark off the surface into 
regular stages. 
Measurements. — The type measurements — height, 72 mm. ; length, 
83 mm. ; breadth, 55 mm. — are those of a rotund-ovate example. The 
height is often somewhat less in proportion to the length. Adult 
specimens of average inflation have the breadth equal to about two- 
thirds of the height. The maximum known size is indicated by an 
imperfect specimen, which has a height of 79 mm. 
Occurrence. — This is one of the commonest and most conspicuous 
of the fossils of the Malone formation. It ranges through all of the | 
fossiliferous part of the Theta subdivision that is exposed in the I 
Malone hills, occurring not only at the principal collecting ground, a 
mile and a half east of Malone station, but also west of the Trio. 
About 90 specimens were collected at the former locality. ExamplJ 
Avere obtained from the west side of the north end of Malone Moun- 
tain, at the same horizon and locality that yielded the specimens of 
Nautilus; from the first high ridge west of Malone Mountain, about 2 
miles west of Malone station, and from a locality about 1 mile east of 
Finlky station. A probable example was obtained by Doctor Stanton 
from the western foothills, 2 miles north of the southern end of Malone 
Mountain, and a distorted one was found by me on the anticline in 
the east side of the mountain, about a mile from its southern end. 
Rotund-ovate, transverse-ovate, and oblique or rhombic-ovate are 
all more or less closely approached by the lateral profile of this shell 
as preserved, which also in some cases is nearly equilateral. A part 
of this variation, but evidently not all of it, is to be attributed to the' 
dynamical stresses to which the Malone rocks have been subject ed. 
In young examples the form is usually more oblong, less equilateral! 
and less compressed, and the concentric ribbing becomes more pro- 
nounced and regular, approaching the type of ornamentation com-ij 
monly seen in medium-sized and small species of Astarte. 
The species seems to be sufficiently near the Jurassic section, Coelas-j 
tarte, of Bohm. a It differs from Astarte excavata Sby., the be 
known representative of that section, in being less strongly inequi 
lateral and in having none of the cardinal teeth striated. The centra i|| 
cardinal of the right valve, while it is the largest tooth of the shell 
is relatively smaller than that of A. excavata as figured by Bohrti 
In form it approaches the sinupalliate species Astarte neocomiensi 
d'Orb, from which it differs by hinge details and its crenulate< 
margins. 
Stoliczka h observes: 
is 
l S I 
" CcMastarte und Heteropis, Ber. Naturf. Oes. Freiburg, i. B. Bd. 7. 1803, pp. 1(><)-17> 
PI. VIII. 
6 Cret. Pelecypoda of Southern India, p. 285. Memoirs of the Oeological Survey ( 
India. Palaeontologia Indica, vol. 3, Calcutta, 1871. 
