g6 CURRENT LITERATURE, 



in Ischnockitoii there are many resemblances to the conditions which obtain in 

 certain Annelids, indeed in the early cleavages in many cases they are cell for cell 

 the same, and although in the later stages these cell homologies disappear, in the 

 behaviour of the cell groups and in the structures they give rise to, development 

 proceeds in both cases much along the same path. From these and other con- 

 siderations the author is of opinion that the resemblances between Ischnochiiun and 

 the Annelids are more fundamental antl closer than are the differences. Discussing 

 the ancestral form of the trochophore, Prof. Heath advances the theory that it 

 " was a quadriradially symmetrical organism whose principal axis corresponds to 

 that of the grastula, and that the shifting of this axis is secondary." This helps us 

 considerably to understand many of the transformations which the developing Chiton 

 undergoes, and also indicates that both the Chiton and Annelid trochophore are 

 constructed upon essentially the same type. Numerous other points of great interest 

 to the student of molluscan embryology are dealt with, all of which are admirably 

 illustrated.— W. E. C. 



Moss, W. — The Genitalia and Radulas of the British Hyalinia. Trans. Manchester 

 Micro. Soc, 1898 [1899], pp. 24 — 28, pis. iv — v. 



This interesting paper records the results of a careful examination of a series of 

 dissections of the terminal ducts of the generative organs of seven species of Hya- 

 linia. Five of these species belong to the subgenus I'oliia, Held., viz., drapar- 

 naldi, eel/aria, glabra, alliaria, and nitidiUa, and two to Zuniloides, Lehm., viz., 

 nitida and excavata. Of the Polita group, nitidula differs widely from the remaining 

 four, which, so far as the principal features are concerned, resemble each other very 

 closely and are classed by the author as the Cellaria group. On the other hand 

 nitidula is, both as regards its radula and generative organs, strongly differentiated 

 from the cellaria type. 



Some interesting variations in the terminal ducts of glabra are figured and 

 described. 



A note on the terminal ducts of ^u'^irfa and excavata is reprinted from the ^^Joimi. 

 of Conchology," and the curious calcareous penis sheath, present in these two species, 

 is figured for the first time. 



The figures, which are reproductions by photo-lithography from photo-micro- 

 graphs, leave much to be desired, good drawings would, in our opinion, have 

 added greatly to the value of the paper. — \V. E. C. 



Scharff, R. F. — The History of the European Fauna. 8vo, pp. vii-l-364, 21 figs. 

 London: 1899, Walter Scott, Ltd. 



This work is the outcome of a paper published in 1897 in the '^Proceedings of 

 the Royal Irish Academy" (3 ser. vol. iv). The original paper has been amplified 

 and improved upon, and certain alterations made. The book opens with a some- 

 what lengthy introduction, followed by a chapter of Preliminary Considerations, and 

 then follow in order, the Fauna of Britain, the Arctic Fauna, the Siberian Migra- 

 tion, the Oriental Migration, the Lusitanian Fauna, and the Alpine Fauna. 



Selecting the British Isles for study, its fauna, broadly speaking, is made up of 

 the following elements: a southern or Lusitanian, which is regarded as the oldest 

 portion, next the Alpine and Oriental migrations, then the Arctic, and finally the 

 Eastern or Siberian. The author endeavours to trace the original home of the dif- 

 ferent elements of our fauna and the path by which dispersal has been effected. 



It is not within our scope to discuss the author's views generally, but we cannot 

 refrain from pointing out one or two points which mark an advance in the discussion 

 of such problems as are here dealt with. Firstly then Dr. Scharft' no longer regards 

 the various zoological regions and subregions as immutable, but rather as convenient 

 terms for the time being. The exterminating severity of the Glacial period he 



