142 
PALEONTOLOGY OF NEW YORK. 
and T. corona, Salter; T. cancellata, Sowerby, does not appear in the catalogue), 
is meager and extremely unsatisfactory, though we may assume that the un¬ 
certainty in regard to these points will soon be cleared away. Barrande’s 
Trematis Bohemica* is unquestionably a Dinobolus. At present we are able to 
recognize eleven species as undoubtedly congeneric, in addition to which are three 
of questionable affinity which are little known. All these are confined to the 
Trenton and Hudson faunas of the Silurian, and the earliest to appear is 
Billings’ T. Huronensis, from the Black River limestone. 
The list of species is as follows: 
Trematis terminalis, Emmons. 
Trematis Montrealensis, Billings. 
Trematis Ottawensis, Billings. 
Trematis Huronensis, Billings. 
Trematis millepunctata, Hall. 
Trematis pundostriata, Hall. 
Trematis crassipuncta, Ulrich. 
Trematis quincuncialis, Miller and Dyer. 
Trematis umbonata, Ulrich. 
Trematis fragilis, Ulrich. 
Trematis oblata, Ulrich. 
? Trematis pustulosa, Hall. 
?? Trematis rudis, Hall,=ScmzocRANiA (?). 
?? Trematis Dyeri, Miller. 
Genus SCHIZOCRANIA, Hall and Whitfield. 1875. 
PLATE IV G, FIGS. 21-35. 
1847. Oi'bicula, Hall. Palaeontology N. Y., vol. i, p. 99, pi. lxxx, figs. 9 a-d. 
1863. Trematis, Billings. Rept. Progress Canadian Geological Survey, p. 159, fig. 126. 
1873. Trematis, Hall. Twenty-third Rept. N. Y. State Cab. Nat. Hist.. Expl. pi. xiii, figs. 21, 22. 
1875. Schizomania, Hall and Whitfield. Geol. Ohio ; Palseont., vol. ii, p. 73, pi. i, figs. 21, 22. 
(?) 187S. Trematis (Schizocrania ), Barrett. Ann. New York Academy of Sciences. 
1884. (Discinocaris ?), Davidson. General Summary of the British Brachiopoda, p. 352. 
Diagnosis. Shells sub-circular in outline, inequivalve, unarticulated. Pedi¬ 
cle-valve flat or concave; apex subcentral. A deep triangular notch extends 
from just behind the beak to the margin, where its arc is equal to about one- 
sixth of the periphery. The apex of this broad pedicle-notch is occupied by a 
triangular transverse plate varying in size with the age of the shell, but ex¬ 
tending for one-fourth to one-third the length of the opening. Surface marked 
by concentric growth-lines. On the interior no muscular impressions are vis- 
Syst. Sil. Boheme, vol. v, pi. 94, fig. vi. 1879. 
