192 THE NAIADES OF MISSOURI 



sit}^ of Missouri. The type shells, Avhich are line-drawn and also 

 photographed herewith, are now in the /possession of Mr. 

 Utterback. 



Truncilla Lefevrei' Utterback. New Species. 



("Lefevre's Shell.") 

 PI. 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 

 entirel}^ 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 evidentl}^ 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 Naiades 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 eflforts 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). 



