698 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Genus APORTHOPHYLA Ulrich and Cooper, 1936 
Plate 163, C, figures 21-24; plate 164, A, figures 1-3 
Aporthophyla UtricH and Cooper, Journ. Paleont., vol. 10, No. 7, p. 625, 1936; Geol. Soc. 
Amer. Special Pap. 13, p. 182, 1938. 
This is another genus having rafinesquinoid appearance but with orthoid car- 
dinalia, strong dental plates, and orthoid muscle scar in the pedicle valve. Illus- 
trations of two species are introduced for comparison with Toquimia, Palaeo- 
strophomena, and other Plectambonitacea. 
Genus TOQUIMIA Ulrich and Cooper, 1936 
Plate 164, B, figures 4-14; plate 195, E, figure 32 
Toquimia Utricu and Cooper, Journ. Paleont., vol. 10, No. 7, p. 626, 1936; Geol. Soc. Amer. 
Special Pap. 13, pp. 183-184, 1938. 
In the summer of 1946 Cooper visited the type locality of Toquimia kirki 
Ulrich and Cooper in Ikes Canyon, Toquima Range, Nev., and collected speci- 
mens which add information to our knowledge of the genus and which help to 
correct previous errors. 
The exterior of the shell is definitely rafinesquinoid, but the brachial valve be- 
comes flat or gently convex in the anterior half. Inside the pedicle valve the 
muscle field is large and has subflabellate diductor-adjustor impressions. An- 
terior to the adductor scars and enclosed by the diductors is an oval pit. Anterior 
to the diductors is a large callosity suggestive of the one seen in Titanambonites 
or Sowerbyites. The visceral region is defined by an elevated ridge a few milli- 
meters inside the anterior margin. Over this ridge and on the flat area anterior 
to it are located the main distributaries of the pallial trunks. 
An error mentioned in connection with the pedicle valve in the original de- 
scription is the statement that a minute foramen is present. The new material 
includes specimens showing the interareas and beaks to perfection (117567h), 
but presence of a foramen was unconfirmed. 
An excellent brachial interior was obtained by dissolving the shell from a piece 
of sandy matrix. This specimen reveals a thin median septum rising to a low 
crest just anterior to the middle. The cardinal process is short-shafted but with 
a bulbous myophore which bears a strong median ridge and a weaker one on 
each side. The brachial processes are short, flat blades. Like the pedicle valve, 
the brachial valve has a thickened area about 5 mm. posterior to the anterior 
margin. The thickening is strongest where the median septum terminates. The 
pallial distributaries form channels in the thickening and extend across the low 
marginal area to the anterior margin. The thickened area of the pedicle valve lies 
somewhat anterior to that of the brachial valve and the two serve as a straining 
device when the valves are in contact. 
Toquimia is suggestive of Palaeostrophomena and is undoubtedly related to 
that genus. Toguimia has, however, a different lateral profile, rafinesquinoid 
ornamentation, lesser development of the median ridge, more flabellate muscle 
scars, and greater development of subperipheral thickenings. The differences be- 
