No.11'57. A NEW GENUS OF MOLLUSKS— STANTON. 805 
several specimens, and in at least four these show essentially the same 
hinge structure as C. jmtnsouL I do not consider the Portuguese and 
Texan forms specifically identical, however, as Professor Choffat ^ has 
done, though they are certainly congeneric. The sculpture is nuich 
coarser in 0. joannce and the ribs are much more angular even when 
thev are not larger. Choffat at first referred the horizon of 0. joannce 
to the Cenomanian, but in later papers he treats it as Turonian. 
G. Boehm ^ has figured a form from the Venetian Alps as Ostrea ajf. 
iinoimnl that still more closely resembles the Texan species in external 
features. Associated with it are some smaller shells that Boehm has 
described as Terquemia forojuliensu^^ figuring the interior of a worn 
specimen. This figure is such as might be drawn with a few slight 
errors in restoration from an imperfectl}^ preserved attached valve of 
Chondrodonta onunsoni^ and it is very probable that the types of Ter- 
(jnernia forojidiensis are young specimens of the 0><trea aff. munsoni, 
and that thej^ all belong to Chondrudonta. From the same region 
Futterer has described Pinna ostremformh^'' which, according to 
Boehm, is identical with his Ostrea aff. nninsoni., and more recently 
Schnarrenberger^ has identified probably the same form as Ostrea 
nunsoni. These Italian fossils also have been referred to the upper 
Cenomanian by Boehm, though the beds containing them have at dif- 
ferent times been referred to horizons as widely separated as the 
Urgonian and the Turonian. Schnarrenberger considers them older 
than the Cenomanian. In Choff'at's latest paper, above cited, O. rnun- 
sojH Hill, 0. aff. munsoni Boehm, and Pinna ostrea^formis Futterer, 
are all treated as synonyms of 0. joannce., and the Portuguese beds in 
which the species occurs are placed in the middle Turonian. 
A note by Virgilio ^ treating of the group of Ostrea joannce., to which 
Professor Choffat kindly referred me, has not yet reached Washington, 
and so could not be consulted. 
A few other forms, including one from the Nummulitic of Egypt, 
have been referred to the "group of Ostrea joannce^''- but as nothing- 
could be learned as to their internal features, the}^ have not been con- 
sidered. The sculpture alone is not to be depended upon as character- 
istic of this group. For example, Conrad^ figures a form under the 
' Revue Critique de Paleozoologie, II, 1898, p. 174, and Mon. Strat. systeme creta- 
cique du Portugal: La Cretacique superieur au nord du Tage, pp. IS.S-lSl, Lis1)on, 
IHOO. 
■^ Beitriige zur Kenntniss der Kreide in den Siidalpen. I. Die Schiosi- und Calloneghe- 
Fauna, Palfpontographica, XLI, 1894, p. 96, pi. viii, flg8. 1, 2. 
•^ Idem., figs. 5 and 6. 
* Palpeont. Abhandl., Dames und Kayser, VI (new series II), 1896, Pt. 2, p. 259. 
;S * Berichte d. Naturforschenden Gesellschaft zu Freiburg i. Br. XI, July, 1901, Pt. 3, 
■ p. 196. 
*Bolletino della Societa Geologioa Italiana, XX, 1901. 
' Lynch' s Report of the United States Expedition to Explore the Dead Sea and the 
River Jordan, pi. i, figs. 7 and 8. 
Proc. N. M. vol. xxiv— 01 20 
