NAIADES OF MISSOURI 49 



includes more under this group, that is, the genera, Fusconaia, 

 Amblema, Megalonaias, Rotundaria, Plethobasus and even some 

 species of Pleurobema. 



Quadrula pustulosa (Lea)' 

 (" Wart3^-Back," "Warty Pigtoe," "Pimple Back.") 

 PI. XVII. Figs. 41 A and B. 

 1 83 1 — Unio pustulosus Lea, Tr. Am. Phil. Soc, IV, p. 76, pi. VII, 



fig- 7- 

 1834 — -Unio nodulosus Say., Am. Conch., VI. 

 1898 — Quadrula pustulosa Baker, Moll. Chicago, Pt. I., p. 86, pi 



XXV. 



ANIMAL CHARACTERS. 



Nutritive vStructures :— Branchial opening with yellowish 

 plumed tentacles; anal smooth; sura-anal very closely con- 

 nected—even disconnected — by mantle edge; inner lamina of 

 inner gills free from visceral mass; color of soft parts dingy white; 

 palpi connected for about one-third of their length. 



Reproductive vStructures: — All four gills entirely marsu- 

 pial, septa crowded, ovisacs narrow; conglutinates white, leaf- 

 like, broken; glochidia large, semi-elliptical, spineless, hinge 

 line short and evenly curved, measures 0.230 x 0.300mm. 



SHEEL, CHARACTERS. 



External Structures: — Shell ovate-quadrate, higher than 

 long, post-umbonal ridge almost horizontal, posterior half pustu- 

 late to smooth, dorsal ridge with nodulous costae; beaks pro- 

 truding anteriorly sculptured concentrically with upcurved ridges 

 posteriorly; epidermis rusty brown with somethimes broad green 

 banded rays diverging from beaks. 



Internal Structures: — Cardinals heavy just under beaks; 

 interdentum broad, upright; laterals straight, at right angles to 

 interdentum; umbonal cavity compressed, deep; nacre white. 



Sex Length Height Diameter Locality 



9 52 X 46 X 32mm (Miss. R., La. Grange, Mo.) 



cf 60 X 60 X 38 " ( " " " " " ) 



9 54 X ^ X 34 " ( " " Hannibal, " ) 



No juvenile shells have been obtained for descriptions; this 

 species is so rare in its typical form for this State that adult shells 

 have been secured with difficulty. 



' The name of this species should read Q. bullata (Raf.) if we accept 

 Rafinesque's evident description of it in his Monograph (1820, p. 41). 



