ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 663- 



sense-organs (olfactory or gustatory ?). (3) Both kinds of sensory fibres 

 have ganglion cells within the cord or in the root of the nerve. (4) 

 The two kinds of sensory fibres on entering the cord form dorsal tracts, 

 and many cutaneous fibres show the characteristic bifurcation. (5) The 

 viscero-motor cells are situated dorsal to the somatic motor cells, lateral 

 to the ventral part of the canal. (6) The nerve cells retain the position 

 and characters which are typical in the embryos of Vertebrates, and which 

 are seen in certain parts of the brain of many fishes. (7) The ventral 

 roots arise separately and remain independent. They are true somatic 

 motor nerves. 



Primitive conditions are undeniable, for apart from those noted under 

 (1), (5), and (6), there is the absence of hair cells responding to vibrations 

 in fluid (neuromasts or acustico-lateral organs) and retinal visual organs. 

 The light-percipient organs within the central nervous system have 

 apparently been retained from worm-like ancestors. The brain is very 

 slightly developed. 



The facts are against the theory that Amphioxus has degenerated 

 from a higher type. The straightforward interpretation of the nervous 

 system supports the view that Amphioxus and Cyclostomes are the lower 

 branches of the vertebrate phylum. 



Amphioxides and Amphioxus.* — R. Goldschmidt believes that 

 Amphioxides may be best interpreted as a neotsenic Branchiostomid 

 larva, but that it represents the most primitive known type of Chordata. 



INVERTEBRATA. 



Mollusca. 



South African Marine Mollusca.f — E. A. Smith gives a catalogue 

 of South African marine Mollusca, with notes on their localities, etc. 

 With two earlier works referred to in the paper the present list provides 

 a complete catalogue of the known species. 



y. Gastropoda. 



Re-discovery of Limax tenellus in Britain. J — T. Petch notes that 

 this slug, found at Durham in 1858, but afterwards excluded from the 

 British list, was found in abundance in the pine-woods of Rothiemurchus 

 (by Rev. R. Godfrey in 1904), and that several specimens were found 

 in the same year by C. T. M. Plowright and the author in Epping 

 Forest. All the British examples belong to the variety cerea, of a 

 uniform waxy colour, with only faint traces of lateral banding. It has 

 black tentacles and yellow slime, and seems to live underground until 

 the fungi come up in autumn. 



Degeneration of Tentacular Nerve of Snail.§ — A. Veneziani finds 

 that in the degeneration of the nerve fibres which follows compression 

 of the tentacular nerve of Helix pomatia, the phenomena are similar to 

 those observed in Vertebrates. 



* Zool. Anzeig., xxx. (1906) pp. 443-7 (3 figs.). 



t Annals Natal Government Museum, i., part 1 (1906) pp. 19-71 (2 pis.). 



X Essex Naturalist, xlii. (1905) p. 342. 



§ Anat. Anzeig., xxix. (1906) pp. 241-8 (5 figs.). 



