1 882.] Recent Literature. 227 



RECENT LITERATURE. 



Balfour's Comparative Embryology. Vol. 11, Vertebrates. 1 — 

 After finding the first volume of this work so useful, accurate and 

 suggestive, we were prepared to welcome the appearance of the 

 second volume, which certainly fulfills the high expectations 

 formed after reading and frequent reference to the first. Our 

 anticipations are fully met, and the entire work for the first time 

 places in the hands of the student a reliable and critical account 

 of the general mode of development of members of each great 

 class of the animal kingdom. The facts have been gathered and 

 compiled from a great variety. of sources, for the literature of em- 

 bryology has multiplied excessively since i860, the larger pro- 

 portion of articles and memoirs having, indeed, been published 

 within the last decade. 



The first third of the volume is devoted to a general account of 

 the development of each class above the Arthropods, with which 

 the last volume closed — i.e., the groups Cephalochorda, containing 

 the single genus Amphioxus ; the Urochorda or Tunicata, and 

 the Vcrtcbrata. This part of the volume contains a good deal of 

 original matter contributed by the author and a few other embry- 

 ologists, together with the most recent results of embryological 

 studies, so that we will glance at some new points which meet 

 one's eyes in the early pages. 



The peculiarities in the development of the Teleostean egg, says 

 Balfour, can best be understood by regarding it as an Elasmo- 

 branch egg very much reduced in size. " It seems, in fact, very 

 probable that the Teleostei are in reality derived from a type of 

 fish with a much larger ovum." 



The lamprey is regarded as the type of a degenerated but prim- 

 itive group of fishes, whose development, however, does not throw 

 any light on its relationship. If so, we do not see why the author 

 places it in his classification or phytogeny above so special and 

 recent a group as the bony fishes. He then says that " the simi- 

 larity of the mouth and other parts of Petromyzon to those of the 

 tadpole probably indicates that there existed a common ancestral 

 form for the Cyclostomata and Amphibia. Embryology does not, 

 however, add anvthing in the anatomical evidence on this subject." 

 On the other hand, he does not assent to Dohrn's view that the 

 lampreys have descended from a relatively highly organized type 

 of fish. 



Had space been allowed we would like to have had fuller state- 

 ments concerning the later stages of the lancelet, as well as 

 of the ascidians. Concerning Myxine no reference is made to 

 Steenstrup's paper, wherein the eggs are figured. Neither is a 

 paper on Amphioxus in this journal (Jan. and Feb., 1880), by H. 

 J- Rice, and containing new facts and drawings, noticed. 



** Treatise on Comparative Embryology. By FRANCIS M. BALFOUR. In two 



