COLLINGE : ANATOMY OF SLUGS. 79 



The Retractor Muscles (PI. iv, fig. 7). — Godwin-Austen (9) and 

 Pilsbry (14) differ from one another in their account of the retractor 

 muscles in A. altivagus, Theob. In the main features I can confirm 

 Pilsbry's account, though there are here some shght differences in 

 position from the condition which obtains in the above mentioned 

 species, which the figure (PI. iv, fig. 7) sufficiently well explains. 



Pedal Gland (PL v, figs. 8 — 9). — Lying free in the body cavity, 

 above the musculature of the foot-sole is a long, tongue-shaped gland 

 17 mm. long and 2.5 mm. broad. At its commencement there is a 

 rounded glandular mass, situated on the dorsal side of the gland and 

 slightly embracing it laterally. I was unable, in the specimen dis- 

 sected, to satisfy myself of its relation, if any, to the pedal gland. 



In transverse section (PI. v, fig. 9) the lumen appears somewhat 

 triangular in shape bounded by a thick glandular wall. The upper 

 side of the lumen is lined with columnar epithelium cells, the lower 

 with cuboid shaped cells. A transverse section was made through the 

 anterior portion of the gland through the rounded glandular mass 

 mentioned above, but particulars of its structure and its exact relations 

 to the pedal gland must be deferred until more material has been 

 examined. 



Pallial Organs (PI. iv, fig. 7). — These agree in the main with the 

 description given by Godwin-Austen (9) of those in A. altivagus. 

 Here, however, the kidney is larger and slightly different in shape. 

 The pyriform shaped ventricle is situated posteriorly, the auricle being 

 directed forwards and slightly towards the right side. 



Tlie Generative Organs (PI. v, figs. 10 — 13). — The vestibule is 

 small. The vagina is a wide tube with a series of longitudinal ridges 

 on its internal wall (PI. v, fig. 11). At the commencement of the 

 vagina these parallel ridges ?re joined by a series of transverse ridges. 

 At about the lower third the thick lip-like opening of the free-oviduct 

 is noticeable, and in front of it the ridges are more pronounced, 

 forming a tongue-like body. The penis is small, 10.5 mm. long in 

 the specimen examined, and somewhat pyriform in shape. The 

 rectractor muscle is divided into two parts, the larger division 

 being attached to the distal end of the penis, the smaller passes 

 over the vas deferens and is inserted into the wall of the penis at 

 about its middle (PI. v, fig 10). Internally the walls of the penis 

 are seen to consist of a dense muscular coat, covered by a glandular 

 epithelial lining, which form a series of longitudinal ridges proximally, 

 distally the whole of the inner surface is studded with a series of 

 minute fleshy rugosities, and at the extreme distal portion is a thick 

 muscular ring, the penis papilla, also covered with these (PI. v, fig. 12); 



