28 CURRENT LITERATURE. 



The subject is dealt with in the author's usual masterly manner ; his long 

 experience and erudite grasp of the many perplexing problems in malacology, 

 render him peculiarly fitted to deal with so difficult a subject as the present one. 



Commencing with a brief historical resume, the author passes on to the 

 consideration of the food and digestive organs, the muscles of the buccal 

 cavity, the shell, the metamorphoses of the soft body, the generative organs, the 

 geographical distribution, and the phylogeny. 



As the author points out, we have to deal with a group not of like origin, 

 but one illustrating the phenomenon of convergence. 



The absence of any accessory reproductive organs is regarded as due to 

 the habits and habitat of the different forms. Where the conditions to fertilisa- 

 tion are so unfavourable, by reason of the individuals not meeting each other 

 in worm-burrows, etc., it would not be practical to waste time in preliminaries, 

 further, it seems very probable that self-fertilisation is very common. Among 

 the many peculiar characters common to these molluscs, may be mentioned the 

 presence of a free pedal-gland in the body-cavity, a third pair of feelers or lips, 

 the reduction and position of the shell and mantle, and (in TcstaccUa) the 

 presence of a sense-organ — osphradium — in the lung. (Plate). 



Assuming that all land molluscs were originally carnivorous. Dr. Simroth 

 explains the changes which have taken place in the " Robber-Slugs," by pre- 

 suming that they had an inate capacity for evolutionary modification, while at 

 the same time special characteristics, which involve vital changes in the 

 organism, have been acquired and transmitted, so as to conform to the new 

 environment. 



Very interesting are the author's views as to the ancestral groups from 

 which the various Agnathous genera have arisen. The Glandiuidac, a very 

 primitive family, are of Achatinoid origin. The origin of the Helicoidae, owing 

 to their great variety of form, and their extreme divergence from the Htiicidac, 

 is difficult to determine, it can, however, be asserted that they have sprung 

 from the primitive groups of the Southern Hemisphere. The Selenites are 

 derived from Zoiiitcs ; Plittoiiia from the Atlantic Viiritiac; Daiidchardia 

 possibly from Hyaliiiia. The origin of the Limacoids is more clearly indicated, 

 excepting perhaps that of the genus Selcnochlawys. Hyrcanolesks, Plin'.wlcstcs, 

 Psciidomllax, and Trigonocldainvs, all show relationship with Pannacella and 

 Ainalia. Apcra (which is wrongly stated to have no shell) is thought to belong 

 to one of the scattered heterogenous branches of primitive molluscs, possibly 

 related to the JancUidae ; Atopos and VerouiccUa probably belonging to the 

 same category. 



Widely differing opinions are naturally held by different malacologists, as 

 to the phylogenetic relationships of these different genera, and not until more 

 detailed researches have been made can the majority of them be regarded as 

 other than very wide guesses, still Dr. Simroth's views are sure to command 

 the careful consideration they undoubtedly deserve. 



Simroth, Heinrich. — liber eine merkwijrdige neue Gattung von Stylom- 

 matophoren. Zool. Anz., 1901, Bd. xxv., pp. 62 — 64. 

 Dr. Simroth describes an interesting slug-like mollusc to which he gives 

 the name Ostracolcthc frtiltstorffcri, gen. et sp. nov. It was received from 

 Mr. Fruhstorfer, who collected it in Tonkin. It measures 2'6 cm. in length, and 

 is remarkable on account of the shell, the relative position of the pallial organs 

 to the mantle, and partly on account of an obscure appendage of the generative 



