Vol. xxvii] ENTOMOLOGICAL NEWS. 43 



"hut a final decision. .. .seems premature" (p. 78). He believes it 

 more appropriate to consider the premandibular, or second antennal, 

 "appendages" "as exaggerated ganglionic swellings," with a dimin- 

 ished probability that they do represent appendages (p. no). The 

 supralingual head segment of Folsom is wanting (p. in). Twenty- 

 one embryonic segments (6 cephalic, 3 thoracic and 12 abdominal) 

 and twenty neuromeres (n abdominal) are recognized (pp. no, in, 

 !37> 256-7). "The writer was never successful in finding anything 

 which could be safely construed as abdominal appendages. They cer- 

 tainly occur, nevertheless, in certain Hymenoptera" (p. 112). In a 

 comparison of nervous systems of different insects "a larval stage" 

 is denied to the Orthoptera (p. 117). Previous investigators have not 

 mentioned the degenerating cells within the embryonic nerve tissue, 

 isolated and in small number in the ventral cord, but in the brain 

 abundant and to a certain extent localized in definite regions ; the 

 significance of this degeneration is not apparent (pp. 164-166). A 

 pair of tracheal imaginations on the second maxillary segment give 

 rise to the anterior ends of the tracheal trunks ; they had been over 

 looked by Nelson's predecessors. On the basis of this discovery, the 

 homology of the tentorial invaginations with those of tracheae "is 

 made decidedly problematical" (pp. 172-175). 



Comparatively little interest has been taken in insect embryology 

 within the last decade, but this valuable book will unquestionably 

 direct more attention to this highly important field of entomology. 

 P. P. C. (Advt.) 



MIMICRY IN BUTTERFLIES. By REGINALD CRUNDALL PUNNETT, F. R. 

 S., Fellow of Gonville and Caius College, Arthur Balfour Professor 

 of Genetics in the University of Cambridge. G. P. Putnam's Sons, 

 New York. 159 pages, 16 plates, in color. 15 shillings net. This is 

 is very interesting review of the whole subject of what is termed 

 Batesian and Mullerian mimicry. The condensation from a vast 

 amount of literature is efficiently accomplished. Mimicry in a number 

 of North and South American species is treated and several plates 

 ar-e devoted to them. The- author does not accept the usual ex- 

 planation for the phenomenon. From the "Conclusion" we extract 

 the following : "From the facts recorded in the preceding chapters it 

 is clear that there are difficulties in the way of accepting the mimicry 

 theory as an explanation for the remarkable resemblances which are 

 often found between butterflies of distinct groups." .... "The sim- 

 plicity of the explanation is in itself attractive. But when the facts 

 come to be examined critically it is evident that there are grave, 

 if not insuperable, difficulties in the way of its acceptance .... 

 Nevertheless, the facts, as far as we at present know them, tell 



