THE NAUTILUS. 117 



Goniobasis plebdus (Anth).' Ouachita and Caddo Rivers, 

 Arkadelphia. Very common. 



Goniobasis lawrencei (Lea), described from the Ouachita River 

 in Garland County, was not found. Search was made for it in 

 the Ouachita River at Cove Creek station, Hot Springs County, 

 near the boundary of Garland County, about twelve miles east 

 of Hot Springs, but without success. 



Helicina orbiculata Say. Dead shells only were collected from 

 creek and river drift at Arkadelphia, these being evidently 

 brought down from the limestone hills in the western part of 

 the County. 



Lampsilis ventricosa satur (Lea). Ouachita River below Ark- 

 adelphia and at Skillern's Shoals; Old River. In form it is 

 closely related to excavatus. Specimens from the Ouachita are 

 "gorgeously appareled", some of a deep solid yellow color, 

 others with varying and elaborate patterns of green, 



Lampsilis hydiana (Lea). The Southern form of luteola, com- 

 mon in all the rivers, and also in Big Deceiper Creek on the 

 Huie farm and at Gum Springs; also in Salt Bayou east of 

 Arkadelphia. 



Lampsilis orbiculata (Hild). Old River. This species is ad- 

 mitted to the list on the authority of Dr. Ortmann. In a letter 

 dated June 5, 1911, Dr. Ortmann writes: "Among the Lamp- 

 silis ventHcosa satur was one individual (female, sterile) which I 

 must regard as Lampsilis orbiculata (Hildreth). This species 

 also is not listed from your region. The specimen agrees in 

 shape etc. completely with the Ohio forms of orbimlata, only the 

 color is not quite typicaV Again on June 19, 1911 : "And there 

 is [among the shells received] a fine typical male of Lavipsilis 

 orbiculatd, preserving even the characteristic pink stain of the 

 nacre." If orbiculata and ligamentina gibba are so similar as to 

 make differentiation difficult as is stated by Wilson and Clark,* 

 then our Ouachita specimens are not this species. 



' Vide Proc. Ac Nat. Sc., Phila., 1900, pp. 458, 459. Both elevatum and 

 plebeius are here figured. 



* See ' ' The Mussels of the Cumberland River and Its Tributaries " , Bureau 

 Fisheries, Doc. No. 781, p. 49. 



