WATSON : ANATOMY OF HELICARION. 99 



towards its anterior end, which is not so much curved as in 

 H . gomesianus ; lined by an irregular network of folds. Secondary 

 ureter extending to the neighbourhood of the anus, and containing 

 numerous transverse folds. 



Pedal Gland embedded in the muscles of the upper part of 

 the foot, and only separated from the body-cavity by a thin layer 

 of transverse muscles, through which the gland shows as a pair of 

 longitudinal light-coloured bands divided by a darker median 

 line, the light bands being formed by the glandular tissue, and the 

 dark line by the duct which runs along the centre of the top of 

 the gland. Transverse sections show a similar structure to that 

 found in H. gomesianus, excepting that the median groove in the 

 floor of the duct seems to be deeper and the folds on each side of it 

 somewhat higher. 



Nerve-eing surrounding the oesophagus, too small to allow 

 the buccal mass to be retracted through it, and closely resembling 

 that of H. gomesianus. 



Cerebral ganglia having well-developed accessory lobes, and 

 giving rise to the paired olfactory, optic, and peritentacular 

 nerves in front, to the single penial nerve, and the paired labial 

 and lower tentacular nerves more laterally, and to a pair of 

 slender nerves innervating the buccal retractor, which arise close 

 to the origin of the cerebro-pleural connectives. Both pairs of 

 labial nerves are slightly larger than usual, being quite as thick 

 as the penial nerve, and not much thinner than the olfactory 

 nerves and those to the lower tentacles. The cerebral ganglia 

 are situated somewhat laterally as in H. gomesianus, and are 

 united dorsally by an arched cerebral commissure, and ventrally 

 by a more slender sub-cerebral commissure, which passes down each 

 side near the cerebro-pedal connective, and crosses over the dorsal 

 surface of the pedal ganglia. 



Buccal ganglia bilobed, though not quite so conspicuously as 

 in H. gomesianus. Five or six pairs of nerves to the oesophagus, 

 salivary glands, etc., arise from each buccal ganglion near the end 

 of the cerebro-buccal connective, one being united with the 

 connective for a short distance. Odontophoral nerves consisting 

 of one pair of rather thick nerves, and another thinner pair, which 

 arise from the inner sides of the buccal ganglia at the origin 

 of the buccal commissure, and a third pair of still more slender 

 nerves arising from the commissure itself, which is of moderate 

 length. 



Cerebro-pedal and cerebro-pleural connectives shorter than 

 usual. Pedal ganglia rather more rounded than in H. gomesianus, 

 but showing the same slight traces of segmentation on the lower 

 surface, and giving rise to the pedal and cervical nerves in a 

 similar manner. Pleural, parietal, and abdominal ganglia closely 

 aggregated, but not united, giving off the same nerves as in the 



