Zoology in France. — The late numbers ot Lacaze-Duthier's 



studies on the earth worms, made use of by Darwin in his last 



work on the earthworm, is beautifully illustrated by chromo- 



reputation for exquisite 



theAcinetae are described and illustrated by E.Maupas, while 



the notes on the anatomy of the brain of the mole, by W. Vig- 

 nal, is accompanied by excellent figures. A. Schneider describes 

 and figures a number of n<:w psorosperms, while Dr. Yung dis- 

 cusses the innervation of the heart and of the action of poisons 

 on the lamellibranchiate mollusks. The last number issued (No. 

 4, 1881) contains elaborate studies on the Pycnogonids, with sev- 

 , by Dr. Ho 



H. Milne-Edwards, who concl 



cea, while he regard- Limulusand the M 

 Arachnids. He accepts Walcott's deterr 



besides other papers, a second installment of A. Milne-Edwards 

 researches on the fauna of the southern regions, concerning the 

 distribution of the albatross, etc. 



Development of the paired Fins in Sharks and Skates.— 

 The latest contribution to this subject is that of Professor Balfour, 

 who states that in Scyllium these arise as slight longitudinal 

 ridge-like thickenings of the ectoderm. Afterwards the fins be- 

 come a ridge of mesoblast covered by epiblast (ectoderm) ; the 

 embryonic muscle-plates grow into the bases of the fins, and form 

 two layers, while in the intermediate indifferent mesoblast changes 

 begin which give rise to the cart aginous sk ' ton. There is 

 thus formed in the fin a bar, which springs at right angles from 

 the posterior side of the pectoral or pelvic girdle, and runs par- 

 allel to the long axis of the body. The free end of this bar be- 



tudinal bar along the base of the fin, which gives off perpendicu- 

 larly a series of rays which pass into the fin. The resemblance 

 to the arrangement of the unpaired fins is consequently very 



•striking, and support is given to the author's original doctrine of 



Mr. Stearns on Variation in American Planorbes.— Apropos 

 of Mr. Hvatf. artiel , the evolution of Ter- 



tiary species oi Plan softheAcad- 



