XXX INTRODUCTION. 
shat one part within another, so as to admit of the head 
being projected forward, that the animal might eat its 
way into the wood that it penetrates.” This we have not 
been able to verify, nor can we see the necessity for the 
disarrangement of the stomach with all its attachments, 
when a prolongation of the cesophageal canal would 
enable the animal to accomplish the work on far easier 
conditions. 
The structure of the alimentary canal is longitudinally 
fibrous. In the genus Ligia, a little anterior to the anal 
termination, a series of transverse muscular bands sur- 
round it without uniting on the under surface, and 
probably fulfil the office of sphincter muscles. 
About two-thirds of the distance between the stomach 
and the telson, one or two appendages are attached to the 
alimentary canal in the Amphipoda. We say one or two, 
because we have distinctly dissected out two in Sulcator 
(Fig. 5), but have failed to determine more than one in 
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Fig. 5. 
Gammarus (Fig. 6), Mera, and other genera. The organ 
is free at one extremity, and is borne in a forward posi- 
tion, resting on the dorsal surface of the primavia. It 
is more important in appearance in some Amphipoda than 
in others; in Sulcator it is very long. We have never seen 
it in any of the Isopoda that we have examined, but, as far 
as our experience supports us, it is present both in the 
male and female Amphipoda, in the adult as well as in the 
