222 SOME NEW BOOKS [September 



in placing the point of origin far back, in Silurian or Devonian times, so that 

 there is a certain fitness in the closing speech, that of Mr. Sedgwick, in which 

 " p re-Cambrian times " are suggested as the period of origin, not of mammals 

 only, but of all the "great classes of the animal kingdom." Mr. Sedgwick 

 suggests that " the main part of the evolution of organisms must have taken 

 place under totally different conditions to those now existing, and must remain 

 for ever unknown to us." We duly altered our belief in Recapitulation to meet 

 Mr. Sedgwick's criticisms, and have learnt to hold the cell-doctrine lightly at his 

 bidding, but this new instance of " thiitige Skepsis " makes so heavy a demand 

 upon our credulity that we prefer to regard it as a delicate piece of sarcasm. 



Among other interesting papers is one by Messrs. Mesnil and Caullery on 

 polymorphism, and the occurrence of epitokous forms in the common littoral 

 annelid Dodecacaria concharum. They find that the common form (Form A) is 

 viviparous, and apparently reproduces parthenogenetically ; males at least have 

 not been found, and reproduction takes place at a time when the males of the 

 other forms are not yet ripe. The second form (Form B) is rare, and occurs in 

 both atokous and epitokous forms. The modifications of form displayed are in 

 all respects similar to those displayed by the Nereids and Syllids. The epitokous 

 forms leave their tubes and become free-swimming. Very rarely a third form 

 was found (Form C), which likewise becomes epitokous, but the changes are 

 less marked than in B. Of this form females only were found. The authors 

 are uncertain whether these forms are to be regarded as allied species or as 

 constituting a polymorphic species. The point of special interest is that the 

 phenomenon of epitoky has not previously been described in sedentary 

 Polychaetes. It seems probable that it occurs much more frequently among 

 Polychaetes than is at present suspected. 



The volume is furnished with a bulky appendix, a considerable portion of 

 which is taken up by " Correspondence on the Nomenclature of Lepidoptera," 

 being the classified answers to questions circulated among certain entomologists 

 by Sir George Hampson. Whether this will advance the science of entomology 

 or not, we cannot undertake to say, but it can be confidently recommended 

 alike to the psychologist and the student of human nature. If, as we are led 

 to believe, systematic or other work is almost impossible to the entomologists, 

 on account of the difficulties of nomenclature, there seems no reason why they 

 should not occupy their time instead in classifying the views of their fellow- 

 workers on various subjects, but the result seems slightly ludicrous to the 

 onlooker. 



The appendix also contains in full Prof. Hubrecht's paper on the " Develop- 

 ment of the Placenta in Tardus and Tupaia, with Observations on its 

 Importance as a Haemopoietic Organ," which is fully illustrated by plates. 

 The volume contains abstracts of numerous other papers in addition to those 

 mentioned, but most of these have been previously published elsewhere. 



N. 



INSECTS. 



Insects (Part II). By David Sharp, M.A., M.B., F.R.S. Being Vol. VI. of 

 the Cambridge Natural History. Edited by S. F. Harmer and A. E. 

 Shipley. Pp. xii. + 626 with 293 figures. London: Macmillan, 1899. 

 Price, 17s. net. 



A hearty welcome will be given by all students of insects to this concluding- 

 portion of Dr. Sharp's monumental work, the commencement of which appeared 

 four years ago in the fifth volume of the " Cambridge Natural History." The 

 volume now before us deals with the higher Hymenoptera, the Coleoptera, the 

 Lepidoptera, the Diptera, the Thysanoptera, and the Hemiptera. It must be 

 admitted that this arrangement of the orders of insects is unsatisfactory ; the 

 Lepidoptera, for example, are removed far from their allies the Trichoptera 



