618 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Genus PROTORHYNCHA Hall and Clarke, 1893 
Protorhyncha HAutt and CLARKE. Pal. New York, vol. 8, pt. 2, p. 180, 1893. 
It is pointed out below that the type specimens of Protorhyncha dubia Hall 
have long been lost and the genus is virtually unknown. Raymond has pointed 
out that the type specimens may actually have been young hebertelloids, which 
makes the genus still more confusing. The facts are mentioned and discussed 
below. Until the types are found, or other specimens that can be definitely identi- 
fied as P. dubia, the true characters of the genus will not be known. 
Genotype.—Atrypa dubia Hall, Pal. New York, vol. 1, p. 21, 1947. 
Subfamily ANCISTRORHYNCHIINAE Cooper, new subfamily 
Protorhynchiidae with characters of the family. 
Genus ANCISTRORHYNCHA Ulrich and Cooper, 1942 
Protorhyncha (part) Hatt and Crarke, Pal. New York, vol. 8, pt. 2, p. 180, 1894.— 
Raymonp, Ann, Carnegie Mus., vol. 7, No. 2, p. 226, 1911—Hayes and ULricu, Geol. 
Atlas U. S., Folio 95, Faunal Chart, 1903. 
Ancistrorhyncha UtricH and Cooper, Journ. Paleont., vol. 16, No. 5, p. 624, 1942. 
Shell small, rhynchonelloid in outline and profile, valves subequal in depth; 
biconvex in profile; anterior commissure uniplicate. Surface marked by fine 
radial costae. Impunctate. 
Pedicle valve with open delthyrium, vestigial interarea, incurved beak. Del- 
thyrial cavity deep, bounded by strong dental plates separated from sides of valve 
by deep umbonal cavities ; teeth small, curved. Details of musculature unknown. 
Brachial valve with divided hinge plate; sockets deep, defined by a fulcral 
plate and a thin but elevated socket ridge; outer hinge plate slightly concave ; 
crural base forming inner edge of outer hinge plate; crura long and slender, 
ending in a broad hooklike expansion pointing anterolaterally and at about right 
angles to the crus. Musculature unknown; median septum absent. 
Genotype.—Ancistrorhyncha costata Ulrich and Cooper, Journ. Paleont., 
vol. 16, No. 5, p. 625, pl. 90, figs. 25-27, 30-31, 1942. 
Discussion.—This genus is characterized by its rhynchonelloid exterior, fine 
regular costae, open delthyrium, strong dental plates, divided hinge plate, and 
long crura. It is distinguished from Rhynchotrema and Rostricellula by absence 
of a septum and cruralium and the fine, even nature of the ornamentation. 
The members of this genus were formerly classified under the name Proto- 
rhyncha, but this name is no longer available for two reasons. First, the type 
species is unrecognizable, as type specimens have long been lost; second, the 
species used by Hall and Clarke for their description of the genus is still invalid. 
Hall and Clarke designated Atrypa dubia Hall as the type of the new genus 
Protorhyncha, but as pointed out by Raymond (1911) this species is unrecogniz- 
able. Hall’s definition of the species is very vague, his figures are poor indeed, 
and he states that the specimens are in the nature of casts, all of the shell having 
been removed. Only two or three individuals of the species are said to have been 
