ANATOMY AND. PHYSIOLOGY 
OF 
AWN ODDIOUNGT TA TO Vi TeART TS LES; 
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 Unionida, and selected one of their number, 
Anodonta fluviatilis, for dissection and explanation. 
By boiling the animal for a short time, the intestinal canai, 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 impossiblefor 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 
