MUSSELS OF CUMBERLAND EIVER AND TRIBUTARIES. 47 



measures 23.2 mm. long, 15.3 mm. high, and 8.8 mm. in diameter, the smallest female 

 31 mm. long, 19.9 mm. high, and 12.9 mm. in diameter. The largest male measures 



57.7 mm. long, 42.7 mm. high, and 26.4 mm. in diameter, and the largest female 



52.8 mm. long, 39 mm. high, and 23.9 mm. in diameter. There are 49 females, the 

 others being males. 



Walkeri, to Mr. Bryant Walker, one of our most eminent conchologists. 



9. Lampsilis ventricosa (Barnes). Pocketbook. 



Typical specimens of this species were obtained in two tributaries of the Cumber- 

 land, Harpeth River near its mouth, and Stones River, in the east fork at Witlterhill 

 and the west fork at Murfreesboro, Tenn. Just how common or widely distributed it 

 is in the streams above mentioned is not known. The examples found were excep- 

 tionally fine and would make very good button shells. 



In the main Cumberland L. ventricosa seems to be quite rare, its place being usually 

 taken by the closely related L. ovata. Indeed, the distribution and relationships of 

 ovata and ventricosa as found in the Cumberland and its tributaries are exceedingly 

 pei"plexing. A few examples found near Clarksville, and a dwarf shell found at Elk 

 Creek shoals above Dover, however, offered exceptional difficulties in classification, 

 fitting in neither with ventricosa nor ovata; the male shell would perhaps fall on the 

 ovata side of the dividing line; the females on the ventricosa side, if indeed not rather 

 beyond the limits of the typical shell; these shells, both male and female, were rather 

 too thick and solid for ovata. A marked feature of those at hand is a deep pink tinge 

 of the nacre posteriorly, this tinge being pretty sharply limited to the posterio-dorsal 

 area, a feature not common with either ventricosa or ovata. 



The female shells are considerably more inflated than the males and have a peculiar 

 flattening of the lower part of the posterior margin. One of the female shells waa 

 sent to Mr. Bryant Walker, who remarks concerning it as follows: "No. 5456 is a 

 most remarkable shell. I have never seen a female ovata with such an enormous 

 expansion. Ventricosa not uncommonly tends that way, but not to such an extent. 

 * * * This shell is comparable only with satur. [A variety of ventricosa, accord- 

 ing to Simpson; satur is L. excavata, according to Frierson.] This shell is either an 

 extraordinary abnormality of ovata or is ventricosa. In view of the occurrence of 

 ventricosa both in the Harpeth and Stones, I am inclined to refer it to the latter." 



10. Lampsilis ovata (Say). Southern pocketbook; "grandma." 



A fairly common species throughout the entire length of the Cumberland, more 

 nimierous in the upper portions and upper tributaries. 



This species is one of the very few found in the Cumberland above the falls. Mr. 

 Boepple obtained it at'Pineville and Williamsburg and we found a few in the vicinity 

 of the latter place and several examples just above the falls. Just below the falls it 

 was abundant and common at the stations farther down. Associated with the typical 

 form, which is relatively uncommon, is an aberrant form, more closely resembling 

 ventricosa. 



The specimens of this aberrant form were at first identified as L. subovatus Say, 

 described and figured by Call.o On examination of the literature, however, there is 

 no " Unio subovatus Say," and the name in Call's report is plainly a misprint for 

 ovatus, the Unio subovatus Lea being an entirely different thing. 



Say's original description of "Unio ovatus" is brief and the figure poor, but recog- 

 nizable; it is probably better known from Conrad's description and excellent figure. ^ 



The greater number of our specimens, however, differ considerably from the typical 

 form. Beginnmg with the shapely, high-ridged clear yellow shell, which represents 



1 MoUusca of Indiana, Twenty-fourth Annual Report of Geology and Natural Resources of Indiana^ 

 p. 481, pi. .39. 

 t Conrad, Monography, p. 4, pi. 2. 



