REPORT ON THE CIRRIPEDIA. 43 



this canal, or cylindrical cavity, to within the body of the animal. AVhen a transverse 

 section of the body is made near the mouth, the alimentary canal in the middle of its 

 dorsal surface is found attached to the wall of the body by means of a rather strong band 

 of connective tissue. Towards the hinder extremity of the body this band grows broader 

 still, and then it appears to be perforated by a central cavity. Towards the anterior end of 

 the body the band grows narrower, yet it may be followed up in all transverse parallel 

 sections, as long as these contain a section of the stomach. Those sections which pass 

 through that part of the body contained between the stomach and that stripe of the 

 mantle which unites the two scuta, only show the band of connective tissue as a loose 

 band attached only on one side, viz., on the dorsal internal surface of the body-wall. 

 The two large cavities which were separated from one another by means of this band 

 are now united. An excrescence of this cavity penetrates this part of the body in a direc- 

 tion vertical to the original dorsal surface, and this part of the body-cavity has one of 

 the two sections of the oviducts on each side. It advances considerably towards the 

 original ventral surface of the body, and now meets the two sections of the oviducts on the 

 dorsal aspect ; after having described a curve it runs longitudinally close to the rostral 

 surface of the narrow part between the two scuta. The two oviducts are now on that 

 side of the cavity which is directed towards the interior of the mantle-cavity, and in the 

 same place they remain visible in the superior part of the peduncle. 



The course of the oviducts through the true body of the Cirripedia can be followed up 

 by making a dissection of it by the aid of needles. To make out its position with 

 regard to the place occupied by the other organs a series of sections serves the purpose 

 still better. In Scalpellum transverse sections through the cephalic part of the 

 body show the oviducts on both sides about midway between the intestinal tract and the 

 wall of the body (PI. VI. fig. 4). It is surrounded on all sides by the connective tissue, 

 and, as a rule, one of the larger cavities of the connective tissue is separated from the 

 duct only by a very narrow strip of the tissue. In Scalpellum, as well as in L&pas and 

 Balanus (the three genera in which the course of the oviducts has been investigated), 

 the oviducts pass beyond the first pair of cirri. They then run upwards, i.e., towards 

 the ventral surface of the body, and bending outwards, i.e., towards the lateral surface 

 of the body, and forwards, they enter what Darwin considers the basal articulation of the 

 first cirrus. In some of the genera {e.g., Lepas, Alepas) this swelling belongs doubtless 

 to the first cirrus ; from analogy we may safely conclude that it belongs also to that 

 pair of extremities in those cases in which (as in Scalpellum) no distinct relation to it can 

 be made out. The oviduct enters this articulation at a considerable distance upwards 

 from its base ; it now describes a curve for the last time, and leads into the curious sack 

 which Darwin considered an acoustic organ, and which opens by means of a transverse 

 slit-like orifice at the proximal part of the basal articulation. 



The structure of the wall of the oviduct may be briefly described as epithelial ; 



