THE NAIADES OF MISSOURI 395 
brown horn-color, sometimes with yellowish narrow bands parallel 
to growth lines, rayless. 
INTERNAL STRUCTURES:—Cardinals double in right, slightly 
so in left valve and arranged parallel with laterals; interdentum 
short; laterals single in right, double posteriorly in left valve; 
beak and branchial cavities very deep and large, basin - like; 
nacre white with light rosy pink in branchial cavities, border light 
bluish. 
Sex Length Height Diameter Locality 
LOM Xaur G2 ix) OS tii (Mississippi R., Hanibal) 
Q 95 x AS x 66mm ( ” ” ” ) 
” 
ON G60) x50) ox) 42min ( 
MISCELLANEOUS REMARKS:—Capax has the most inflated 
shell of the Nazades, yet because of the fact that it is rayless and 
has no sex dimorphism, nor furrowed beak sculpture, nor pure 
white nacre of L. ventricosa it must be removed far from the latter 
although its immensely inflated shell would superficially class it 
near veniricosa. Its great inflation is not any greater, however, 
than that of the relative inflation of the /aevissima shell in the last 
stage of its parasitic life. Most of all, anatomical material kept 
by the writer, shows no mantle flap (PI. XX VI, fig. 93 B) as seen 
in L. ventricosa, nor as to be noted in any Lampszlis, and the mantle 
edge antero-ventrad to the branchial opening is not even as much 
specialized as in laevissima, or alata; hence its place perhaps 
should precede Jaevissima, at least, but is placed last in the group- 
ing under this genus on account of its most peculiarly inflated 
shell which may show an advance over the other species that show 
the other extreme in possessing a compressed shell in their adult 
life. Capax is very rare shell for this State. It has a rather limited 
geographical distribution over the whole country; however, Simp- 
son reports it as abundant locally, yet the writer’s experience in 
collecting it for in the Mississippi is that it is rare even there and 
it was considered a stroke of good fortune to secure glochidially 
gravid material showing proptera characters. 
La Grange) 
Genus Carunculina Simpson. 
(Type, Unio parvus Barnes.) 
1898—Carunculina Simpson (in Baker, p. 109, as section). 
1900b—Carunculina Simpson. Proc. U. 8. Nat. Mus., XXII, p. 563. 
(as subgenus); 1912b, Ortmann, Car. Mus., VIII, p. 337 (as subgenus). 
ANIMAL CHARACTERS:—Branchial opening small with rather 
