﻿320 TKITOGONMA 



Tritoi^^oiiia verrucosa Agassiz, Arch, fur Xat., I, 1852, p. 4(S. 

 Trltigonia I'ernicosa Smith, lUill. [' . S. I*'ish Com., 1899, p. 



2()1, pi. LXXXI. 

 Oiiadnila tritoi:;<)iiia ()rt.m.\nx, .\;iut., X.XIl, 190^, j). loi. 

 Qiiadnila ohcsa Wwaita, .\aul., XX I II, 1910, ]). 102. 

 Quadrula harkeri ( iI'iskk, I'lic Academician, 1, 1911, p. 15. 



I have never seen a specimen among the hundreds examined 

 that had young or ova in the gills. I'ut I have seen sperma- 

 tozoa in specimens with intlated shells and ova in those with the 

 wing. Mr. H. x\l. Kelly, of Mount X'ernon, Iowa, who has 

 made a very careful study of the anatomy of many of our 

 L'nionicKne, assures me that the form with the compressed shell, 

 having the expanded flap behind, is the female. 



It has been claimed that this species was previously de- 

 scribed under the name of Obliqiiaria verrucosa by Rafinesque, 

 but I am unable to make anything out of his figure or 

 description ; hence I use the name given by Barnes. Barnes' 

 name was used by Rafinesque for the species which the former 

 called ihiio i-ernicosus. but as Rafinesque placed his species in 

 Ohliquaria, and as the generic names of both forms are 

 changed in this work. I do not consider IJarnes' name preoc- 

 cu])ied. Female shells seem to generally grow larger than 

 those of the males. 



\'ar. obesa Simpson. 



vShell mucli smaller than the type and very much more 

 inflated, the sculpture finer and arranged in broken ridges or 

 nodules so as to form more or less perfect chevron-shaped 

 patterns ; posterior flap of the female less developed than in 

 the type. 



Length (male) 78, height 47, iliam. 33 mm. 



Length (female) 75. height 50. diam. 30 mm. 



Texas; Louisiana; Mississipi)i. 



Type locality, T.ig Kddy. Xechez River. Texas. 

 Tritogouia tuberculata var. obesa Simpson, Syn.. 1900, p. 609. 



This variety is distinct enough to almost have specific rank, 

 but as I have seen only a limited amount of material and as 



