104 MALONE JURASSIC FORMATION OF TEXAS. [bull. 26G. 
rather narrowly rounded; the flanks flattish-convex ; umbilical border 
rounded; the wall of the outer whorl sloping rather gently to the 
next whorl within it, that of the inner whorls descending somewhat 
more steeply below; inner whorls ornamented with strongly elevated, 
moderately close, but not crowded, dichotomous ribs whose branches 
separate at about the middle of the flank and continuously cross the] 
venter, the lateral ribs not noticeably enlarged on the umbilical bor-j 
der, this ornamentation becoming gradually changed to large low 
undulations on the outer whorls and almost vanishing before the ( pre- 
sumably plain or nearly plain) body chamber is reached; septal line 
with two strong lateral lobes, which are rather strongly dissected, and 
a deep suspensive lobe; the first lateral lobe large, twice or more than 
twice as long as the second, longer than the siphonal lobe, and having 
three strong terminal branches of which the outer is subtended by a 
smaller branch; the second lateral lobe pinnate, not distinctly 
branched at summit; a noticeable lobe, similar to the second lateral 
lobe, but slenderer and about two-thirds as long, stands between the 
first lateral and the siphonal lobe ; suspensive lobe consisting of one tall 
pinnate lobe, with strongly trifid summit, which is outwardly pre-! 
ceded by a trio consisting of a small lobe flanked on either side by a 
lobule and is inwardly followed by two obtuse lobes the inner of which 
is xcvx low and often 3-denticled. This description of the septal line 
relates to the later septa, the preceding ones being somewhat simpler. 
Measurements. — Height of largest cross section of whorl preserved 
in the type, 85 mm.; breadth of same, 54 mm.; span of umbilicus 
opposite same section, 90 mm. 
Occurrence. — The type represents a considerable and wholly septate 
part of the form and Avas obtained by Doctor Stanton from No. 13 of 
his Malone Mountain section on the west side of the mountain, about 
"2 miles southwesterly from Malone station. Me obtained a fragment 
also on the east slope of the mountain near its southern end, about 200 
or 300 feet above the heavy bed of gypsum which there forms the base 
of the mountain : and a poorly preserved specimen and fragment from 
foothills near the railroad, at the northwest end of Malone Mountain, 
a little over 2 miles east-southeast of Finlay station, not more than 
200 feet above the gypsum bed of that locality. 
It is not unlikely that this is the same species as that figured and 
briefly described from the Tithonian of Mexico as "Perisphinctei 
sp. ( ?)" by Castillo and Aguilera," and compared by them in its rib- 
bing with P. Victor, P. haliarchus, and P. polygyratus. The septal 
line bears considerable resemblance to that of the latter species, which, 
from the White Jura Beta, Quenstedt h figures under the name of 
"Ammonites triplicatus ulhus." 
"Fauna Fosil do la Sierra <li* Catorce, i». ."»">, PI. XIX. 
" I>i" Ammonitcn <!<>s Schwabischen Jura, pi. 100, fi«. 8. 
