136 Annals of the South African Museum. 



Central nervous system. Nerve-ring surrounding the buccal 

 mass, the cerebral ganglia often lying in front of the opening of the 

 oesophagus, and the rather long cerebro-buccal connectives being 

 therefore frequently directed backwards. Cerebral ganglia rather 

 close together, the cerebral commissure being short. In Trigo- 

 iic/ilinis the cerebral ganglia and the nerves arising from them are 

 more or less surrounded by darkly pigmented connective tissue. 







B 



TEXT-FlGUBE 1. 



Transverse Sections through the Pedal Gland in the Dorcasiitiac (somewhat 



diagrammatic). 



A. TrigonepJinix porpliyrostoma (M. & P.) ; section near hind end of gland, x 9. 



B. ,, ,, ,, ,, front end of gland, x 9. 



C. Dorcasia rogersi, n. sp. ; section near hind end of gland, x 15. 



D. front end of gland, x 15. 



The buccal retractor is innervated by a pair of nerves arising near 

 the junction of the cerebral ganglia and the lateral connectives. 

 Buccal ganglia widely separate, joined by a rather long commissure 

 behind the opening of the oesophagus. Cerebro-pedal and cerebro- 

 pleural connectives rather long. Pedal, pleural, parietal, and 

 abdominal ganglia forming a compact ventral group, but none of 

 them actually united, the abdominal ganglion tending to fuse 



