32 THE NAUTILUS. 



twisted or having internal nodules, etc. Combined with the 

 external characters, a grouping into 14 sections is indicated. 

 Dr. Ball believes that nothing in the land-shell fauna of the 

 Galapagos group, which these snails inhabit, lends weight to the 

 hypothesis that these islands were ever connected by land with 

 the continent of South America. The snails "were probably 

 transported originally to the Galapagos group by high winds 

 while attached in a state of hibernation to dead leaves or similar 

 light material." H. A. P. 



FAUNA OF THE HAMPDEN BEDS AND CLASSIFICATION OF THE 

 OAMARU SYSTEM. By P. Marshall (Trans, and Proc. N. Zea- 

 land Inst., 1919, Vol. 51, pp. 226-250, pis. 15-17). Twenty- 

 seven new fossil mollusks are described. 



SOME NEW FOSSIL SPECIES OF MoLLUSCA. By P. Marshall and 

 R. Murdoch (Trans, and Proc. N. Zealand Inst., 1919, Vol. 51, 

 pp. 253-258, pis. 19-21). Nine new species are described. 



MOLLUSCA FROM CENTRAL AMERICA AND MEXICO. By Henry 

 A. Pilsbry (Proc. A. N. S., Phila., 1919, pp. 212-223). 16 

 new species and several subspecies, mainly collected by Mr. A. 

 A. Hinkley. The more interesting forms are Averellia ( Tricho- 

 ditcina) hinkleyi and a form of Neritilia, a genus new to the 

 American mainland, found in Guatemala by Mr. Hinkley. 



A MONOGRAPH OF THE NAIADES OF PENNSYLVANIA, PART III. 

 By A. E. Ortmann, Mem. Carnegie Museum, Vol. LI, No. 1, 

 1919. 



This sumptious volume is a fitting envelope for its contents. 

 Indeed the most serious criticism to be made is that it is too 

 luxurious for convenient use, as the weight of the paper used 

 makes the book too heavy to be held in the hand for reading, 

 and necessitates the use of a table or reading desk when con- 

 sulting it. 



