ANATOMY AND PHYSIOLOGY 



OF 



ANODONTA FL UVIATILIS. 



By George B. Simpson. 



ANODONTA FLUVIATILIS. 



Several years ago while making a collection of fresh-water shells, I 

 naturally desired to know something of their anatomy and physiology. I 

 found no book treating specially of that subject, though I found one or 

 more chapters in several books, but to me they did not seem to 

 be just what was needed by a beginner, the articles were either without 

 illustrations or the illustrations were few and very poor. I have written 

 this article with the hope that it may be of use to beginners, and also 

 to some who have contented themselves with collecting the shells 

 paying no attention to the living animal within. To those who are ad- 

 vanced in similar knowledge, this article may seem simple, but it must 

 be remembered that very simple things are frequently formidable to 

 beginners. I had intended to follow this article with others on the an- 

 atomy and physiology of other bivalve and univalve shells, but the delay 

 in printing has been so great that I have not done so. At that time I 

 was more interested in Unionidae, and selected one of their number, 

 Anodonta fluviatilis, for dissection and explanation. 



By boiling the animal for a short time, the intestinal canal, nerves, 

 arteries, etc., are much more easily found than by dissecting an alcoholic 

 specimen; though the animal is distorted by boiling still a very good 

 idea of the position of the different organs is formed, and the dissection 

 of a specimen which has been kept in alcohol for some time is rendered 

 much easier, the student knowing just where to look for the differ- 

 ent organs: to dissect an animal just from the water would be almost 

 if not quite impossible for a beginner. A very slight addition of 

 chromic acid to the alcohol in which some of the animals are kept, will 

 be of help in dissecting certain parts. 

 [Sen. Doc. No. 38.] 22 



