108 THE AMERICAN MIDLAND NATURALIST 
undata rubiginosa (Lea) a name which this form might well bear 
because of its closer relation with F. flava (Raf.) [=F. rubiginosa 
(Lea)]. After a prolonged correspondence among Messrs. Simpson, 
Walker and Frierson this rather common and peculiar form was 
left to the latter for naming; hence the MS. name herein given. 
MISCELLANEOUS REMARKS:—This intergrade is very near 
the form, wndata-trigona, and differs only in being more elongated, 
less upright, more rounded, post-dorsal margin, more reddish 
epidermis, lower beaks, and is a larger, heavier shell. Those of 
this variety that are found in the Mo. Platte of North Mo. have the 
most ponderous shell of any of the /usconaia—some reaching 
a length of 1roomm while the average length of the species (F. 
undata) for the Mississippi only average 60mm. This variety 
seems to be more of a creek form of F. flava and the reason for this 
- form being larger in the Platte R., a smaller stream, than in the 
Osage, the largest tributary of the Missouri in this State, may be 
traced as a mere local effect since the shells of other species in the 
Mo. Platte are found to be abnormally large. Like most of the 
Unioninae this form has a peculiar habit of aborting its conglu- 
tinates when taken from its natural bed. The author has been 
able to pick out for study the little pink club-shaped conglu- 
tinates from whole masses of other white leaf-shaped conglu- 
tinates of Quadrulae or Pleurobemae that would also be aborted 
after being collected from the river and placed in a tub or aquarium. 
The habits of this form are that of deep and rapid burrowers and 
inhabitants of deep water and coarse gravelly bottom. It is found 
to be gravid from May until September and sterile for the rest 
of the year. A proposed publication by Mr. Frierson on these 
puzzling southwestern forms of Fusconaia- will, without doubt, 
clear up the situation. 
Fusconaia flava (Rafinesque.) 
(Pigtoe,’’ ‘‘Red Shell,”’ “‘Red Nose,” ‘Wabash Pigtoe.’’) 
Pl. XV. Figs. 32 A—D. 
1820— Unio flavus Rafinesque, Monog. Bio. Shells of R. Ohio. 
1829— Unio rubiginosa Lea, Tr. Am. Phil. Soc., III, p. 427. Pl. VIII, 
fig. 10. 
1898—Quadrula rubiginosa Baker, Moll. Chicago. Pt. I. p. 77, Pl. 
4) hs af an a, Se nO lee 
1912—Fusconaia rubiginosa Ortmann, An. Car. Mus., VIII, pp. 241 
242, Text Fig. 4. 
