MURDOCH: ANATOMY OF BUHMINUS D.I L'UDJ URENslS. 175 



develops into an outer cusp, which is sometimes cleft at the apex 

 only, sometimes divided quite to the base, and which thus ultimately 

 gives rise tu two, and even three, outer cusps. 



Digest ire tract (Fig. III). — Buccal mass short and subglobular. 

 Salivary gland (sl.g ) small, enveloping the oesophagus, with two 

 salivary ducts emptying into the buccal cavity. Crop (cr.) small 

 and well marked, situated immediately posterior to the salivary gland; 

 thence contracted into a smaller tube, with thick walls, that opens into 

 the comparatively large stomach (st.), the latter receiving the right 

 and left hepatic ducts (hp.d.) as figured. The intestine (Jut.) curves 

 shortly forward, then makes a complete turn to the right, passing 

 across the albumen gland and under the posterior portion of the 

 stomach, again curving forward, passing over the alimentary canal, 

 and terminating in a narrow rectum. The anterior and slightly 

 smaller lobe of the liver partly envelops the stomach and intestine, 

 the posterior end of the stomach being imbedded in the upper lobe. 



Genitalia (Fig. IV). — Penis (p.) with a long appendix («/>/'■). 

 branching from the anterior portion and proceeding back as far as the 

 stomach, the upper part somewhat enlarged and usually having one 

 or two small spiral turns. Posterior to the appendix, it gradually 

 enlarges for a short distance and is then abruptly contracted, 

 proceeding as a more slender organ with the vas-deferens (v.d.) 

 inserted a little below the apex. This slender portion is folded across 

 the posterior end of the buccal mass, and has always one, or two, 

 small external papillae. The interior walls of the penis are minutely 

 granulated: within the appendix is a small double thread-like 

 structure adhering to the walls, contained within the narrow duct 

 and terminating at the lower enlargement. Retractor muscle (r.m.) 

 divided anteriorly into two bands, one of which is applied to the 

 stouter portion of the penis and the other to the lower portion of 

 the appendix, the distal end being attached to the floor of the 

 pulmonary chamber. . A small muscle also appears to be attached 

 to the vas-deferens. Spermatheca (spr.) forming a slender tube 

 enlarged at the apex ; from about its middle there branches off 

 a diverticulum, which is slightly enlarged above and closely applied to 

 the oviduct. Albumen gland (al.g.) large ; hermaphrodite duct (h.d.) 

 closely convoluted, the gland (h.g.) small and dark in colour, not 

 imbedded in the liver. A minute appendix branches from the 

 hermaphrodite duct close to the junction of the latter with the 

 albumen gland. 



Free muscles (Figs. V and VI). — The arrangement of the muscles is 

 very similar to that which obtains in Helix. The right and left 

 bands supply the retractors to the foot, head, and tentacles; the right 

 ocular retractor passing through the genital branch. The muscles 

 Jr. 1 unite with the head close below the inferior tentacles ; the other 

 pair of muscles, r. 2, are inserted at the junction of the lower lip and 

 foot. The retractor of the buccal mass branches from the left baud 

 posterior to the left pedal muscles, its anterior half dividing into two 

 strands applied to the under side of the buccal mass. In addition to 

 the retractor, the buccal ma?-s has two small anterior muscles [ant.m.) 



