590 ORTMANN—NAYADES OF 
except that it has salmon-colored nacre; to my knowledge, this color 
of the nacre is extremely rare. 
Farther down the Tennessee, at the mussel shoals in Alabama, 
this species is abundant (Conrad, Hinkley, and Carn. Mus.). 
Type locality: Ohio River and Kentucky River (the type is from 
Kentucky River, according to Vanatta). 
84. TRUNCILLA TORULOSA GUBERNACULUM (Reeve), 1865. 
Unio gubernaculum Reeve, Conch. icon. 16. Unio. ’65, pl. 28, f. 146. 
Reeve’s figure undoubtedly is this form. Simpson (’14, p. 26) 
makes this a synonym of the var. rangiana (Lea), and it surely is 
the parallel form to rangiana of the upper Ohio drainage. It differs, 
however, distinctly by the dark green color of the posterior expan- 
sion of the female shell. 
From the typical torulosa, this variety differs by the poorly de- 
veloped or wanting knobs, and by the rather more compressed shell. 
This is the headwaters form of torulosa, and begins to take its 
place in the region of Knoxville. I have it from the Nolichucky, 
Chunn’s Shoals, Hamblen Co.; here, as also in the lower Holston, 
faint knobs may yet be present. Farther up, the shell is entirely 
smooth. In the Holston, it goes up to the South Fork at Pactolus, 
Sullivan Co., Tenn., and to the North Fork at Holston Bridge, Scott 
Co., Va. In the Clinch, it goes to Dungannon, Scott Co., Va. It is 
also in the Powell, up to Shawanee, Claiborne Co., Tenn. Locally, 
it may be quite abundant. 
Type locality: ? 
85. ITRUNCILLA TURGIDULA (Lea), 1858. 
Unio turgidulus Lea,’’58 (male)—Unio deviatus Reeve, 64 (fe- 
male).—Truncilla deviata Walker, ’10b, pp. 77, 78, 81.—Truncilla 
deviata Simpson, ’14, p. 31. 
Unio turgidulus has been regarded as the male of the female U. 
florentinus, but it belongs to the female deviatus. In Walker’s key 
(10b), this has been indicated by the grouping, but it has not been 
expressly mentinoned. 
T. turgidula stands nearest to T. biemarginata (Lea), a species 
