NAIADES OF MISSOURI ^9 



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. 



58 X 50 X 26mm (Osage River, Linn Creek, Mo.) 



MiscELivANEOus REMARKS: — The above measurement is 

 that of a moderately compressed shell resembling that of some 

 typical liebetata 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 ruhida 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 — Unio ehena Lea, Trans. Am. PhiL Soc, V. p. 84, pL IX, fig. 14. 

 1900b — Quadrula ehenus, Simpson, Proc. U. S. Nat. Mus., XXII, p. 793. 

 1912b — Fusconaia ehena (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 b}^ 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 o. 15 mm), conglutinates subcylindrical, bright pink. 



SHELL characters. 



External Structures: — Shell thick, solid, subrotund, some- 



