Marshall—On the Anatomy of the Dragonfly. 765 
fore-and mid-intestines join, it can be seen that' the wall of 
the fore-intestine shows no external difference between the crop 
and the gizzard; the presence of the plates alone indicating the 
latter. The thin transparent wall of both crop and gizzard 
has, in the latter, a thicker muscular layer; this cannot be 
noticed in an external view. 
Calvert (6) found a variation in the position of the gizzard 
in individuals of the same species. In Hetaerina americana 
the gizzard was in the fourth, fifth or sixth abdominal seg¬ 
ments and in Archilestes grandis it varied in position from 
the fourth to the sixth segment. In Lib'ellula d-maculata there 
is a slight variation but the gizzard is always in the second, 
third and fourth segments. It cannot be described as situated 
exclusively in the third segment as, in many examples, it ex¬ 
tends forward into the second or back into the fourth. If 
there be any sexual difference it is that in male specimens the 
gizzard more frequently extends forward into the second seg¬ 
ment while there are some females, in which it extends back 
into the fourth. Calvert (6) found in Hetaerina americana 
four folds in the gizzard, each covered with minute teeth; 
there were no large teeth present and no intermediate tooth¬ 
bearing folds. Ris (22) mentions that in Lihellula the teeth 
are much reduced and, while he does not figure any species 
of the genus, his drawing of the gizzard of Cordula aenea is 
very similar to what is found in Libellula J^-maculata. 
In this latter dragonfly there are four large folds and along 
each of these there is a long, narrow, longitudinal plate (fig. 
17). From a surface view these plates appear of a dark brown 
color and, in transverse section, it is seen that the chitin form¬ 
ing the plates is not only much darker but also thicker than 
the chitin lining any other part of the gizzard. Each plate 
is shaped a little like the head of a spear with the point directed 
backward; the anterior end does not have a distinct boundary 
but gradually .becomes lost in the surrounding light colored 
cuticula. The edges of the plates, especially the posterior half, 
are very irregular. The small cuticular projections present 
over the surface of the pharynx and oesophagus are not so 
