LOWER CRETACEOUS FORMATIONS AND FAUNAS 603 
turtles, crocodiles, and plesiosaurs but they have not furnished 
any very definite evidence as to the age of the beds. One of the 
fishes (described by Cope) came from the Glen Rose beds and 
another from an unknown locality in Texas. All the other 
vertebrates mentioned are from higher beds near Camp Supply, 
Oklahoma, and in southern Kansas. Fragmentary bones that 
are supposed to be dinosaurs but have not been definitely identi- 
fied have been collected in the Trinity sands by Mr. Hill. 
The invertebrate fossils are,very numerous throughout almost 
all of the series above the basal Trinity sands, and constitute 
several distinct subfaunas though all are connected by species 
that pass from one zone to another and a few species range 
through a large part of the series. The species have been mostly 
described in various books and papers by Roemer, Giebel, Mar- 
cou, Shumard, Gabb, White, Hill, and Cragin. The revision of 
the invertebrate species with the description of new forms con- 
tained in recent collections on which I am at present engaged 
has not progressed far enough to enable me to give complete 
lists of the fossils of each zone but the general features of the 
fauna can be profitably discussed and some interesting compari- 
sons can be made. 
Mr. Hill’s* reviews of the subfaunas of the Trinity division 
and of the Caprina limestone in the Fredericksburg division 
afford a basis for comparing these horizons with other Creta- 
ceous beds. The list given for the Trinity (Glen Rose) includes 
about forty invertebrate species and this number will be con- 
siderably increased by the study of recent collections. The fol- 
lowing characteristic forms, mostly from the same horizon as 
the Glen Rose plants, are the most important for our present 
purpose : 
Ostrea franklini Coquand Requienia cf. texana Roemer 
Trigonia stolleyi Hill Monopleura cf. marcida White 
Trigonia crenulata (Lam.) Roemer Monopleura cf. pinguiscula White 
Trigonia lerchi (Hill) Cyprina sp. 
Trigonia n. sp. Natica (Lunatia) pedernalis Roemer 
«Proc. Biol. Soc. Washington, Vol. VIII, 1893, pp. 9-40, 97-108. 
