June 18, 1897.] 



SCIENCE. 



959 



chseta and Hirudinea, by F. E. Beddard, pp. 

 345-408, Figs. 187-210; Gephyrea and Pho- 

 ronis, by Arthur E. Shipley, pp. 409-462, Figs. 

 211-231 ; Polyzoa, bj'^ Sidney F. Harmer, pp. 

 463-533, Figs. 232-257. 



Fifty pages of Mr. Gamble's account ai-e de- 

 voted to the Turbellaria, twenty-three pages to 

 Trematodes, eighteen to the Cestodes and five 

 to the Mesozoa, the major part dealing with the 

 groups in which the author is most at home. 

 A detailed description is given of the structure 

 and habits of a common Polyclad {Leptoplana 

 tremellaris) and a common Triclad (Planaria 

 lactea), together with a general account of the 

 different groups. It is to be regretted that the 

 same method was not followed with the Khab- 

 docceles, with Mesostoma as the type, a cosmo- 

 politan form, which has, perhaps, been the ob- 

 ject of study more than any other Turbellarian. 

 The account, on the whole, is the best that 

 we have for the Turbellaria. But a few 

 slips and inaccuracies occur, chief among them 

 being the statement that land planarians are 

 'cylindrical,' and that " freshwater planarians 

 vary from a quarter to half an inch in length," 

 whereas it is known that among the common 

 European species, Dendroccelum lacteum {PL 

 lactea of the author) reaches a length of 26 

 mm. (lijima), D. punctatum, 5 cm. (Hallez), 

 and Fl. gonocephala, 25 mm. Again, the 

 ' sucker ' of PL lactea is said to have been ' dis- 

 covered by Leydig ' instead of v. Baer or Dug6s. 

 Among the Ehadoca^les no mention is made of 

 the fact that certain members of the genus 

 Mesostoma are viviparous, and of the relation 

 between this condition and the occurrence of 

 the thin-shelled 'summer eggs.' 



The chapters dealing with the Trematodes 

 and Cestodes are comparatively meagre, but 

 are an excellent epitome of our knowledge of 

 the parasitic flatworms. Structural matters are 

 scarcely touched upon, the account consisting 

 chiefly of life-histories, the life-history tables 

 being novel and instructive. Distomum mag- 

 num is said (p. 4.) to be parasitic in sheep (!). ■ 



The Nemerteans are dismissed by Miss Shel- 

 don in twenty pages, a small space for so im- 

 portant a group, particularly in the light of 

 the extensive recent researches. The classifica- 

 tion adopted is that of Hubrecht, although the 



more rational one of Biirger is printed, with 

 the excuse that this author's work appeared 

 too late to be adequately considered. One para- 

 graph devoted to ' palaeontology ' tells us that 

 Nemerteans ' are unknown in a fossil state. ' 



Mr. Shipley's chapters on the Nemathel- 

 minthes and ChiEtognatha are valuable compila- 

 tions of the natural history of these orders, and 

 the recent researches on the problematic Acan- 

 thocephala are here brought together for the 

 first time. Synoptic tables are given of the 

 species of Chfetognatha, and Conant's list of 

 American species finds a place in an appendix 

 at the end of the volume. 



lu Professor Hartog's account of the Rotifera 

 and their allies the most striking thing is the 

 author's declaration of the relationships of the 

 Rotifera with the lower Platyhelminths and his 

 comparison of them with the Pilidium of the 

 Nemerteans, the older idea of arthropod affini- 

 ties being abandoned. A pleasing feature is a 

 brief description of the technique for the pre- 

 servation of Rotifers. 



The most extensive section in the book com- 

 prises Dr. Benham's chapters on the Archian- 

 nelida, Polychseta and Myzostomaria. Under 

 the second of these classes the general account 

 is prefaced by a detailed description of a typical 

 Polychffite (Nereis pelagica), as in Mr. Gamble's 

 account of the Turbellaria. The classification 

 employed is a modification of that proposed by 

 by the author in 1894, according to which 

 the various families are grouped under two 

 'branches' and seven 'sub-orders.' Following 

 a general account of the structure and biology 

 comes a systematic portion in which the various 

 sub-orders are illustrated by descriptions of 

 British species. 



Mr. Beddard's account of the Oligochajta 

 offers nothing new of importance, the chapter 

 being an excellent summary of the general part 

 of the author's recent monograph, and a good 

 sketch of a group to our knowledge of which 

 he has contributed so much. 



The same author's chapter on the Hirudinea 

 is not so carefully done as that on the earth- 

 worms, and at times is careless and almost 

 flippant in its treatment. Inter alia we learn 

 such bits of natural history as that "the former 

 extensive use of the leech has led to the trans- 



