NAIADES OF MISSOURI } Iil 
in left, interdentum deeply gashed in right; laterals double in 
left with slight tendency to double in right; umbonal cavity 
narrowly deep, scars deep; nacre white to pale pink. 
Length Height Diameter Locality. 
ROP x<auS Ox 2 Otnitn (Osage River, Linn Creek, Mo.) 
MISCELLANEOUS REMARKS:-~The above measurement is 
that of a moderately compressed shell resembling that of some 
typical hebetata shells which are sent to the writer from Alabama 
and considered as types by Messrs. Wright, Walker and Simpson. 
The latter student (1900b, p. 787) reports the Alabama hebetata as 
also found here in Missouri, but no specific locality is given. Since 
there seems to be so much confusion concerning this shell of Conrad 
with his own cerina or with Lea’s rubida it should be investigated. 
Probably it would be found (through longer suites of shells) that 
the broad compressed flava of the White River would either be a 
form of Conrad’s hebetata or an unusual flava of Raflnesque, or 
perhaps an age-form of the latter. As matters now stand this 
species (if it be a good one anywhere) must be listed with some 
doubt for Missouri. 
‘Fusconaia ebena (Lea). 
(“Nigger Head.’’) 
1831— Unto ebena Lea, Trans. Am. Phil. Soc., V. p. 84, pl. IX, fig. 14. 
1900b—Quadrula ebenus, Simpson, Proc. U. S. Nat. Mus., XXII, p. 793. 
1912b—Fusconaia ebena (Lea) Ortmann, An. Car. Mus., VIII, p. 245. 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening large with 
branched papillae; anal smooth or crenulated; supra-anal large 
briefly connected to anal by mantle edge; gills brown outer pointed 
anteriorly inner laminae of inner gills free from visceral mass; 
palpi moderately large and connected about half of their length 
antero-dorsad. 
REPRODUCTIVE STRUCTURES:—All four gills marsupial; when 
charged scarlet, not distended; before gravidity ovaries carmine 
color; glochidium semicircular, spineless, medium size, hinge 
line straight but slightly oblique, length and height about equal 
‘(0.160 x 0. 15 mm), conglutinates subcylindrical, bright pink. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Shell thick, solid, subrotund, some- 
