5 
ANATOMICAL OUTLINE SKETCH. 
The thorough study of the anatomy of the adult oyster is 
srather difficult, but there is no difficulty in gaining all the 
knowledge which is needed for procuring and fertilizing the 
•eggs. As I hope that a way will be found to turn my ob 
servations to practical account in oyster culture, I will give 
a very brief sketch of the structure of the oyster — such a 
sketch as will enable any one who reads it with an opened 
-oyster before him to acquire the necessary anatomical knowl- 
edge. It is hardly possible to write such a description with- 
out using a few technical terms, such as anterior and posterior, 
dorsal and ventral. As the end of the body where the mouth 
is placed is not marked by a head, it must be spoken of as the 
anterior end , not as the head , and the opposite end as the 
posterior. As the oyster lies on one side, the top and bottom 
of its body do not correspond to the regions which occupy 
these positions in an upright mussel or clam, and it is most 
convenient to speak of that part of the oyster’s body which 
answers to the upper surface of a clam as dorsal and the op- 
posite as ventral. 
The general structure of an oyster may be roughly repre- 
sented by a long narrow memorandum book, with the back 
at one of the narrow ends instead of at one of the long ones. 
The covers of such a book represent the two shells of the oys- 
ter and the back represents the hinge, or the area where the 
two valves of the shell are fastened together by the hinge 
ligament. This ligament is an elastic, dark brown structure, 
which is placed in such a relation to the valves of the shell 
that it tends to throw their free ends a little apart. In order 
to understand its manner of working, open the memorandum 
book and place between its leaves, close to the back, a small 
piece of rubber to represent the ligament. If the free ends 
or the cover are pulled together the rubber will be compressed 
and will throw the covers apart as soon as they are loosened. 
The ligament of the oyster-shell tends by its elasticity to keep 
the shell open at all times, and while the oyster is^lying un- 
