NO. 1205. SYNOPSIS OF THE NAIADES— SIMPSON. 609 



* Unio verrucosus Say, Am. Conch., VI, 1834.— * Conrad, New F. W. Shells, 1834 



p. 72.— *Ferussac, Guer. Mag., 1835, p. 27.—* Conrad, Pr. Ac. N. Sci. Phila., 

 VI, 1853, p. 259.— *KusTER, Conch. Cab., 1862, p. 273, pi. xcii, fig. 1.—^^ Sow- 

 ERBY, Conch. Icon., XVI, 1868, pi. i, fig. 4. 



* Tritogonia verrucosa Agassiz, Arch. fiir. Nat., I, 1852, p. 48. 



* Tritigonia verrucosa Smith, Bull. U. S. Fish Com., 1899, p. 291, pi. lxxxi. 



t TRITOGONIA TUBERCULATA var. OBESA Simpson.i 



Mississij)pi drainage generally; streams falling into the Gulf of 

 Mexico from tlie Alabama system west to central Texas. 



t TRITOGONIA CONJUGANS B. H. Wright. 



* Unio conjugans B. H. Wright, Naut., XIII, 1899, p. 89. 



* Tritogonia conjugans Simpson, Pr. Ac. N. Sci. Phila., 1900, p. 79, pi. iv, fig. 1. 



Hiawassee Eiver, Tennessee. A single male shell of this remarkable 

 species, the type, is in the TJ. S. National Mnsenm collection. I am not 

 positive that it belongs here, though it probably does. 



MESOGENvE. 



Male and female shells alike, short, solid, inflated; embryos occupying 

 a few distinct ovisacs in the center of the outer gills. 



Genus CYPROGENIA Agassiz, 18§2. 

 (Type, Unio irroratus Lea.) 

 Cy])7-ogenia Agassiz, Arch, fiir Nat., 1852, p. 47. 



Shell solid, inflated, rounded triangular, sometimes slightly retuse, 

 generally a little biangular behind; posterior ridge" unusually well 

 developed, especially in the young shell; umbonal region flattened 

 parallel with the axis of the shell, sometimes compressed; beaks curved 

 inward and forward, their sculpture very faint, consisting of slightly 

 doubly looped ridges; sculpture of the shell nodular, radiately wrinkled, 

 or lachrymose; ligament black and conspicuous; lunule distinct and 

 well developed; epidermis shining, painted with a delicate, dark mot- 

 tling on a light ground; hinge plate wide and flat; pseudocardinals 

 heavy, triangular, blunt and ragged ; laterals short, obliquely striated ; 

 cavity of the beaks not deep; adductor scars small, well impressed, 

 those at the posterior round; nacre bright and silvery. Animal with 

 inner gills partly free from the abdominal sac, rounded below; outer 

 gills smaller; marsupium consisting of from seven to twenty-three very 

 long, iDurple ovisacs pendent from near the central base of the outer 

 gills, and formed into a close coil with the ends turned inwardly; bran- 

 chial opening large with many small papilhe; anal opening smooth. 



^A short, inflated, peculiarly formed shell from Big Eddy, Nechez River, Texas, 

 having very few faint tubercles is in the U. S. National Museum collection, and may 

 be a distinct species. It is certainly vrorthy of the varietalname here applied, 

 Proc. :N^. M. vol. xxii 39 



