COCKERELL; NOTES OX LAND AND FRESHWATER MOLLUSCA. 259 



S. duplicatum Cless. Konigs-Wusterhausen, Germany. Sub- 

 globular corneum, apparently var. nucleus. Grey, shiny, 

 striate, edge of valves yellowish. Long., 9|: lat., ii\; 

 crass., 8 mill. 



S. ryckholtii Norm. Nauen, near Berlin, Germany. Small, 

 white, shiny, of the characteristic ryckholtii form. 



Unio athesinus Adami. Mattarello Lake, Mattarello, Tyrol. 

 A form o{ pictoiuni. Lat., 76A; crass., 22; long., 33 mill. 

 Colour yellowish with brown zones. 



U. arcuatus Bgt. River Rhone, France. A form oi pictonini, 

 but shorter, and rather more ///w/^?/f-shaped. Olive, with 

 brown ill-defined zones. Lat., (m\ ; long., 28^ ; crass., 

 19 mill. Nacre white. This is very close to, and perhaps 

 identical with, some of the forms found in the Thames, 

 near London. 



U. pictorum var. limosa Nilss. Neisse River, Patschkau. 

 Lat., about 90 mill.; long., 34; crass., 24 mill. A long 

 greenish-olive var. oi pictorum. Nacre white, iridescent. 



U. rostrata C. Pfr. Hunte River, Oldenliurg. Apparently a 

 var. o{ pictorum. Lat., 61; long., 26; crass., i8| mill. 

 Outlines, rounded; colour, olive; beaks, eroded. Nacre 

 white. 



U. tumidus var. lacustris Rs.sm. Hunte River, Oldenburg. 

 Lat., 58; long. 29; crass., 19I- mill. A small dark tumidus. 



U. piscinalis Rsm., Neisse River, Patschkau; U. ater Nilss., 

 Neisse River, Patschkau; U. ater v^x. consentanea Rossm., 

 Moschganzen, Austria; U. rivu/ans'K.?,m., Krebsbach River, 

 Patschkau; U. batavus Nilss, Lohe River, Strehlen, Ger- 

 many; and U. ajnniciisZ,^., Wied River, Neuwied, Germany, 

 seem all to be distinct from any species found in Britain. 

 U. amnicus and U. rivtilaris seem to be varieties of U. ater ; 

 while ater itself is perhaps not specifically distinct from 

 U. piscitialis. 



West Cuff, Cvister Co., Colorado, U.S.A., I'eb, 2j, iSgo. 



