ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 49 



Pennington's 'British Zoophytes.'* — Mr. A. S. Pennington has 

 prepared an introduction to the Hydroida, Actinozoa, and Polyzoa 

 found in Great Britain, Ireland, and the Channel Isles, which should 

 be useful to English naturalists; the microscopic structure of the 

 various forms described is not neglected. 



After a short historical account of the study of " zoophytes," the 

 general classification of the groups and an account of their bathy- 

 metrical distribution is given. For the Hydrozoa IVIr. Hincks's classi- 

 fication of the Hydroida into Athecata, Thecaphora, and Gymnochroa 

 is adopted, reference being made to that of Professor Allman, where 

 differences obtain. Gosse's classification of the Zoantharia is brought 

 into conformity with the systems of Hertwig and Andres. For the 

 Polyzoa, Hincks and Busk are chiefly followed. The book concludes 

 with some hints on the collection and preservation of the organisms 

 which have been described ; and there are a bibliography, a glossary, 

 and an index of popular names. 



Mollusca. 



Nerve-centres of Cephalopoda.f— M. Vialleton " assimilates " the 

 dotted substance found in the nerve-centres of Cephalopods with the 

 fibres of the neuroglia in vertebrates, denying that it is a new form of 

 tissue, but that it is only transitory in vertebrates. All the ganglia 

 of Cephalopoda are at first formed of embryonic cells, in the midst of 

 which the dotted substance soon appears as an inextricable plexus 

 of fibrils arising from these cells, which early loses its reticular 

 character and takes on the appearance of a uniformly granular sub- 

 stance ; some ganglia, such as the optic, retain this structure in the 

 adult. In the suboesophageal portion the cells become larger, and 

 tend to have the form of ganglionic cells. In the visceral ganglion 

 small cells, identical with those of the optico-cerebral centre, are seen 

 in contact with the dotted substance, and at the periphery of the 

 cortex there are true ganglionic cells with a prolongation, resembling 

 the filament of Deiters, which can be easily followed through the 

 dotted substance to a nerve ; in other words, there is the same con- 

 tinuity of cells and cylinder-axes as in vertebrates. The mode of 

 development of the nervous tissue is the same in both groups, but in 

 the cephalic centre of Cephalopods it does not proceed as far as in 

 vertebrates. 



Size and External Sexual Characters of the New Zealand 

 Octopus-I — Professor T. J. Parker refers to a species of Octopus 

 found near Vancouver's Island, which measured 5 ft. along one arm, 

 and was hitherto supposed to be the largest known specimen. The 

 measurements of Octopus maorum, however, show it to exceed the 

 former in size. The whole length of body is 1 ft. 1 in. ; the longest 

 arm, 5 ft. 5 in., is the first on the left side ; the others all exceed 



* Pennington, A. S., ' British Zoophytes,' 363 pp. (24 pis.), 8vo, London 

 (L. Eceve and Co.) 1883. 



t Comptes Rendus, ci. (1885) pp. 1016-8. X Nature, xxxi. (1885) p. 586. 



Scr. 2.— Vol. VI. E 



