40 THE NAUTILUS. 



" Var, solidus. Very solid, wide, ashen; inside whitish, the 

 poBterior valve with 10, central valve 2-3, anterior valve 12 

 slits. Length 72, breadth 40, divergence 130°. Carpenteria, 

 near Sta. Barbara, Cal. This is scarcely more than an individ- 

 ual variation. The mantle (girdle) is normal. The sculpture 

 is worn away except at the edge. It has evidently lived in a 

 very exposed situation." 



From this description and the figure which he gives of the 

 valves it would seem that this is the same form as my specimens 

 from the pholad holes. I fully agree with Dr. Pilsbry that it 

 is hardly worthy of varietal rank. It is, however, too distinct 

 in appearance to be labeled simply Ischnochiton coiupicuus, Cpr., 

 and I have therefore marked these specimens from the pholad 

 holes I. conspiaius, Cpr.,/onu solicla, Cpr., using the term form 

 as advocated by Dr. Cockerell, " to designate variations plainly 

 due to environment." ' 



LAMPSILIS VENTRICOSA COHONGORONTA IN THE POTOMAC KIVEE. 



BY WILLIAM A. MARSHALL. 



In 1912 Dr. A. E. Ortmann recorded " finding in the Potomac 



River a variety of Lampsilis ventrkosa ' to which he gave the 



name cohongoronta. His records were: 



September 4, 1909. Potomac River, Hancock, Washington, 

 Co., Md. (about two dozen). 



May 9, 1911. South Branch, Potomac River, Southbranch, 

 Hampshire Co., \V. Va. (about a dozen). 



August 16, 1911. Shenandoah River, Harper's Ferry, Jefferson 

 Co., W. Va. (a single male, below medium size). 



May 6, 1912. South Branch, Potomac River, Romney, Hamp- 

 shire Co., W. Va, (about a dozen). 

 Dr. Ortmann remarked "It is probable that this species will 



* Nautilus, vol. xx, pp. 58-60. 

 'Nautilus, xxvi, pp. 51-55, 1912. 



' In a later work Ortmann cla.ssities both venti-icosa and cohongoronta as vari- 

 eties of ovata Sav. 



