Prof. G. J. Allman on the Anatomy 0/ Actseon. 147 



appendage with which it is furnished. This appendage is a py- 

 riform sac, PL 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 Z>, which curves forwards along the 

 convexity of the loop. 



From the posterior part of the buccal mass a slightly sinuous 

 (esophagus, PL VI. d, runs backwards and terminates in an oval, 

 longitudinally striate stomach, e, from which a short intestine, ff 

 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 maybe detected. Of these, two, PL Nl.g g, 

 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, h h, consists each of a sim- 

 ple tube of great delicacy, which commences in the buccal mass 

 just anterior to the origin of the oesophagus, and then becoming ^ 

 attached to the oesophagus runs over the supra- oesophageal ganglia, 

 and soon exhibits a series of little caecal 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 in Actceon 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 oesophagus 

 there opens into this tube a small sac of a pyriform figure, PL Vl.f ; 



M2 



