308 ORTMANN— CORRELATION OF SHAPE AND 



This can be tested, of course, only in such forms which have a 

 wide distribution, and are found both in large and small rivers. I 

 have measured a number of such, but did not find any evidence for 

 our law in the following cases. 



Elliptio dilatatiis (Raf.). — Distribution tremendous, equally 

 abundant in large rivers and small streams : but no trace of the law 

 observed. 



Strophitiis edentiilus (Say). — The same wide distribution in all 

 kmds of streams, but no evidence of the law. 



(It should be noted that no species belonging to the subfamily 

 Anodontinas has shown, so far, any evidence of submitting to this 

 law.) 



Ptychohranchus fasciolare (Raf.). — The same holds good for 

 this species as for the two preceding ones. 



Actinonaias carinata (Barn.) {= Nephronaias ligamentina). — 

 Although not going into the smallest headwaters, this species is 

 found in smaller and larger rivers, but no change of obesity is 

 observed. 



Eurynia recta latissima (Raf.). — Has a very wide distribution 

 from the large rivers well vip into the headwaters, but is remarkably 

 uniform in obesity. 



Lampsilis siliqiioidca (Barn.) (= luteola). — Practically ubiqui- 

 tous in the interior drainage (although missing in the upper Ten- 

 nessee). No relation observed between size of stream and obesity, 

 although the shell is very variable. 



Lampsilis fasciola Raf. (= mttltiradiata) . — Practically every- 

 where in the interior drainage, but obesity not responding to station. 



TrunciUa triqiictra Raf.— Of wide distribution, and in streams 

 of various size, but without marked change in obesity. 



TrunciUa capsceformis (Lea). — Widely distributed and common 

 in the upper Tennessee region, found in small creeks and large 

 rivers, but uniform in the convexity of the valves. 



In addition it should be remarked that in none of the species be- 

 longing to the Atlantic drainage this law has been observed to exist. 

 This is most evident in the common Elliptio complanatus (Dillw.). 

 This is found practically everywhere, in large rivers as well as in 



