ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 813 



Nemertines. Annelids. 



Cephalic ganglia. Cephalic ganglia. 



Ventral commissure. Dorsal commissure. 

 Dorsal „ 



Lateral nerves. Circumoesophageal commissures. 



Ventral ganglionic chain. 



The proboscis and its associated parts are compared with homo- 

 logous parts in those Khabdocoela that have a proboscis. 



Ehabdoc(Ela. Nemertinea. 



Pouch of proboscis. Vestibule of proboscis. 



Epithelium of proboscis. Epithelium of proboscis. 



Internal layer of muscular in- Muscular layer of proboscis, 

 vestment. 



External layer of muscular Walls of the sheath of pro- 

 investment, boscis. 



Radial muscles of muscular Muscular band, 

 investment. 



The essay concludes with an account of the digestive tract ; after 

 the closure of the blastopore it is a closed sac, the oesophagus is of 

 ectodermal origin, and the anus is very late in appearing. 



Nephridia of Acanthodrilus sp.* — Mr. F. E, Beddard records 

 certain peculiarities in the nephridia of a new species of Acanthodrilus 

 inhabiting New Zealand. In this worm as in Plutellus, described by 

 M. Perrier, the nephridial orifices alternate in position from segment 

 to segment ; further evidence of their being the remains of two distinct 

 series, each one corresponding to a pair of setEe, is afforded by the 

 fact that they differ morphologically ; the nephridia associated with 

 the ventral setae are furnished with a large diverticulum near to the 

 external orifice of which the glandular tube opens ; the dorsal nephridia 

 are furnished with a long muscular duct and a very minute diver- 

 ticulum, situated on the dorsal side of the external orifice. 



Nephridia of Microstoma lineare.f — Dr. O. Zacharias describes 

 the nephridia of this Planarian, which have been hitherto overlooked 

 or incompletely studied. On either side of the body is a canal, which 

 gives off branches converging towards the middle line and united by 

 finer canaliculi, and forming a subcutaneous network which is stronger 

 on the ventral than on the dorsal side. 



Fresh-water Monotidae.J — Dr. G. Duplessis-Gouret records the 

 occurrence of a marine form of Planarian, originally described as a 

 new genus, but now known to bo a species of Monotus (M. morgiensis) 

 from the lake of Geneva, This species is nearly allied to M. relidm, 

 discovered by Zacharias in a mountain lake in Silesia, The occur- 

 rence of these marine forms in fresh water points to the fact that they 

 arc the remnants of a marine fauna gradually destroyed by the cutting- 



♦ ZfX)l. Anzeig., viii. (1885) pp. 289-00. 



t Ibid., pp. 316-21. I Ibid., pp. 291-3. 



