38 
GEOLOGY 
(rryphcea sinuata var. Americana, than to any other; and I am inclined to consider the Exogyra Over- 
wegi var. laevigata Bey. as the young of the Gryphaa sinuata var. Americana. Overwog did not find the 
specimen figured by Beyrich as the variety laevigata of the E. Overwcgi in the same localities of the 
Wadi (creek) Zemzem and Wadi Taghije (See: Dr. H. Barth’s travels in North and Central Africa, sheet 
N° 3, vol. 1, London, 1857.), where he met with so large a number of E. Overwegi and Inoceramus 
impressus ; but the specimen was given to him during his stay at Tripoli , and it was probably picked up 
during a journey with a caravan from Fezzan to Tripoli. However, Texas and the route from Fezzan to 
Tripoli being both comprised betw'een the 30"' and 33'' degrees of north latitude, it is not impossible 
that the same species existed in Africa and America during the Cretaceous period. 
Locality. — This gigantic Gryphite appears to be rare in Texas, the specimen figured is the 
only one I have ever seen. It was found in the Cretaceous rocks of the borders of Red river 
near Preston, Texas. 
Explanation of figure. — Plate III , fig. 1 . Shell natural size , lower valve. 
GRYPHAEA PITCHERI Morton. 
Plate IV, fig. 5, 5 a, 5 b, 6. 
Description. — Shell sub-triangular , thick , gibbous , irregular ; inferior valve curved , oblique and inflated , very 
narrow near the beak and broad at the opposite side, divided externally into two unequal lobes by a longitudinal 
furrow which begins at the beak and runs the whole length of the shell ; both lobes are more or less carinated 
with knobs upon each of them. The beak is large , elongated , oblique and specially compressed laterally , which 
is very characteristic of this species. Superior valve irregular, sub-oval, nearly plane, marked with concentric im- 
bricating lamellae. The muscular impression is well marked on the tw'o valves. 
Observations. — This species differs from all other known Gryphceae. It resembles somewhat the 
Gryphwa Couloni Defr. of the Neooomian of Neuchfttel in its general oblique form, and the knobs upon 
the lobes of the lower valve. Hoemer thinks it resembles very much the Gryphoca arcuata Lamk. of the 
Lias of England, and the figure 1 a (See: Die Kreidebildungen von Texas, pag. 73, pi. IX, fig. 1, la, 
lb, 1 c.) that ho gives of it resembles in fact this species. This figure must have been taken from a 
specimen subjected to lateral pressure, for I have seen perhaps more than 4,000 specimens of this spe- 
cies, and have only found one having partly the form of fig. 1 a of Roemer. This one specimen had 
evidently been pressed laterally and the beak showed wounds that explain the prominence. Fig. 1 b 
of Roemer shows neither the_obliquity of the beak nor its compression, and I have not seen a single 
specimen of this form. As Roemer observes, this species varies; but I will add that the flattening of the 
beak and the knobs upon the carinated lobes do not vary, and are fixed characters in all the spe- 
cimens I have seen in Texas or Arkansas. Morton has figured a small specimen, incomplete and with- 
out the superior valve (See: Synops. Cretaceous Group, page 55, pi. XV, fig. 9.). Roemer has given a 
large specimen, probably badly executed by the draughtsman or the lithographer, and he gives no 
figure of the superior valve, saying that he has never found a complete specimen. 1 found a single 
complete specimen of a young individual, and it is given in plate IV, fig. 6. Further I have given two 
drawings fig. 5 and fig. 5 a of two adult individuals , and also fig. 5 b the inferior face of the superior 
valve. The drawings in plate IV are very exact, and were done from nature by Humbert, the most 
skilful artist for fossils, in Paris. 
Locality. — This species is found iu the first strata of the Cretaceous rocks of Texas, where 
it is as numerous as the Gryphma arcuata is in the Jura mountains and the Wurteinberg' All). The 
limestone of the False Washita and of the Canadian river might be called with propriety Gryphite 
limestone. These beds being the lowest of the Cretaceous rocks of Texas , and the form of the 
Gryphtea Pitcheri having more resemblance to the Gryphwa Couloni than to any other species, have 
