THE NAIADES OF MISSOURI 455 
sity of Missouri. The type shells, which are line-drawn and also 
photographed herewith, are now in the possession of Mr. 
Utterback. 
Truncilla Lefevreit Utterback. New Species. 
(‘‘Lefevre’s Shell.’’) 
Pl, VI., Figs..13. a—d; Pl. XXVIII., Figs. 108 A—D. 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening thickly papil- 
lose; anal crenulated; supra-anal moderately connected to anal; 
outer gills shorter and only half as wide as inner gill, inner laminae 
entirely connected to visceral mass; outer gills drawn up high 
and pointed anteriorly forming wide gap between palpi and 
anterior attachment; palpi small, free their whole dorsal length; 
color of soft parts dingy white with squarish, blotched mantle 
edge around anal and supra-anal openings and solid blackish 
border at branchial opening. 
REPRODUCTIVE STRUCTURES:—Marsupium formed by several 
ovisacs arranged in a kidney-shape, which, when gravid, extend 
down to the edge of inner gills forming a plain beaded border 
on the ventral edge; inner mantle edge anterior-ventrad to bran- 
chial opening drawn over into the interior of shell forming a com- 
partment evidently as a water reservoir; no conglutinates nor 
glochidia observed. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Shell small, narrowly rounded 
before, solid anteriorly, thin posteriorly; general shape of both 
sexes ovate-trigonal; epidermis brownish-yellow, smooth, with 
fine, continuous rays; beaks rather large, full, too eroded to make 
‘As may have been noted, the author has departed from the accepted 
Code of Nomenclature on Natades in so far as to employ the initial capital 
for all names of those Species and Sub-Species derived from the names of 
persons when used substantively in both their respective binomial and 
trinomial forms. Although this action may seem somewhat presumptuous, 
yet the departure is surely justifiable on the grounds of efforts to be more 
consistent with clearness as to the nominal derivation and especially with 
the Latin and Greek etymology or diction. In this regard the. suggestion 
of the Editor has been followed and reference would be made to his comments 
on ‘‘Proper Publication’? (Am. Mid. Nat., Vol. IV., No. 3, pp. 95 and 96). 
