Prof. G. J. Allman on the Anatomy of Actzon. 147 
appendage with which it is furnished. This appendage is a py- 
riform sac, P]. VII. fig. 5 a, which communicates by means of a 
canal with the left extremity of the tongue. 
The sac is filled with spines, precisely similar to those of which 
the tongue is composed. They seem to be perfectly formed, and 
are placed without any apparent order in the sac. It is difficult 
to assign to this sac any other function than that of secreting 
the tongue-spines ; and we can easily conceive that as the tongue 
is worn away at one extremity, additions are as constantly made to 
it from the contents of the sac at the other. The lingual sac is 
applied against the outer side of the buccal mass, being wholly 
external to this body. 
The tongue terminates at the right side in a small unarmed 
prolongation, Pl. VII. fig. 5 6, which curves forwards along the 
convexity of the loop. 
From the posterior part of the buccal mass a slightly smuous 
esophagus, Pl. VI. d, runs backwards and terminates in an oyal, 
longitudinally striate stomach, e, from which a short mtestine, f, 
runs transversely to the right side in order to terminate near the 
anterior margin of the lateral expansion. The direction of the in- 
testine thus places the true position of the anus beyond all doubt, 
though so accurately is the external orifice kept closed, that it has 
hitherto escaped my attempts at detection. 
The stomach and intestine are clothed internally with a ciliated 
epithelium, by which their contents are kept in a constant state 
of agitation. 
In connexion with the alimentary canal just traced are several 
accessory organs which require special mention. Four glands 
analogous to salivary may be detected. Of these, two, Pl. VI. gg, 
are connected with the anterior extremity of the buccal mass, and 
appear to consist each of a cluster of small vesicles, which pour 
their contents into the commencement of the alimentary tract. 
The posterior pair of salivary glands, / /, consists each of a sim- 
ple tube of great delicacy, which commences in the buccal mass 
just anterior to the origin of the cesophagus, and then becoming 
attached to the esophagus runs over the supra-cesophageal ganglia, 
and soon exhibits a series of little cecal offsets forming small sacs 
appended to the tube for the remainder of its course, Pl. VII. fig.6. 
The gland thus constituted runs back through the body of the 
animal, extending for a considerable distance behind the stomach. 
The salivary glands i in Aci@on are highly interesting from their 
simplicity of constitution, and afford a fine illustration of the 
reduction of glandular structure to one of its least complex ex- 
pressions. 
At a short distance from the termination of the cesophagus 
there opens into this tube a small sac of a pyriform figure, Pl. V1.7; 
M2 
