580 ORTMANN— NAYADES OF 



tain locality, chiefly from some small creeks, show uniform and pe- 

 culiar characters, but this holds good only for short distances. In 

 the longer rivers (Powell, Clinch, Holston) the variation is consid- 

 erable and irregular, apparently without any recognizable rules. 



The distribution of E. nebulosa extends over the whole of the 

 upper Tennessee region, but the species decidedly favors the head- 

 waters and small streams, and often goes up to the uppermost limit 

 of Nayad-distribution in this region. It is not necessary to give a 

 list of the localities : it is practically everywhere in the Powell, Clinch, 

 Holston, French Broad, Little River, Hiwassee. (It apparently is 

 only accidental that it has not been recorded from the Little Ten- 

 nessee.) It is also in Chickamauga Creek, and it deserves special 

 mention that it goes up, in French Broad, to Asheville, N. Car. 



In the larger rivers, this species is rare, yet it is present. 



In addition, E. nebulosa has a wide range not only in the Cumber- 

 land drainage, but also in that of the Tennessee in North Alabama, 

 and it also has invaded the headwaters of the Coosa-Alabama system 

 in northern Georgia and Alabama. It is very singular that Wilson 

 & Clark ('14) do not mention it in their paper on the Cumberland 

 shells, although a good number of the synonyms have their type 

 locality in this system. 



Type locality: Black Warrior River, Ala. 



68. EuRYNiA (Micromya) vanuxemensis (Lea), 1838. 



Unio vanuxemensis Lea, '38. — Unio nitens Lea, '40. — Unio nm- 

 brosns Lea, '57 (=umbrans Lea, '57). — Unio tenebricus Lea, 

 '57. — Unio pybasi Lea, '58. — Unio fabaceus Lea, '61. — Unio copei 

 Lea, '68. — Unio pybasi Lewis, ,'71. — Unio pybasi and caliginosus 

 Pilsbry & Rhoads, '96. — Eurynia (Micromya) vaniixcmens'is 

 Ortmann, '12b, p. 342. — '15, p. 65 (anatomy). — NepJironaias 

 copei and Eurynia vanuxemensis Ortmann, '13&, p. 311. — Eurynia 

 vanuxemensis Goodrich, '13, p. 95. — Lampsilis vanuxemensis 

 Simpson, '14, p. 105. 



Unio dispansus Lea, '71, placed by Simpson here, belongs to E. 

 nebulosa (see above). Probably there are other synonyms. 



This shell is shorter and higher than E. nebulosa, has generallv a 



