THE NAUTILUS. 81 



Mr. Lovell Reeve 3 as a stunted form of C. tabescens L. , but has been over- 

 looked by Sowerby* and by Mr. Raymond Roberts in the " Monograph of 

 Cypi-iea."'* Rather blindly following Reeve in 1888, 6 I signalized this as var. 

 a of C. tabescens under the proposed varietal name of latior. Mr. Edgar 

 Smith being disposed to allow it specific rank, labelled it in the National Col- 

 lection " ia/ior Melv." Last year, however, it was closely examined by us 

 both, in comparison with the original type of C. rashleighana^?c&&. pronounced 

 identical. The pyriform shape, different dentition, narrower aperture, small 

 clearly defined dark brown lateral punctuation, with other characteristics, dif- 

 ferentiate this species from its allies, C. tabescens, C. feres and C. interrupla.- 

 JAMES COSMO MELVILL, Journal of Conchology, July 1898. 



i ?. Conch., vol. 5, p. 288. 2 blanch. Mem. (4), vol. 1, p. 218, 219. 3 Conch. Icon., pi. 14, 

 no. 66a, 1845. 4 Thes. Conch. 5 Tryou, Man. Conch., vol. 7, 1885. 6 Loc. cit., p. 218. 



PUBLICATIONS RECEIVED. 



THE DISTRIBUTION OF THE UNIONID^E IN MICHIGAN, by Bryant 

 Walker. (Read before the Michigan Academy of Science, March 

 31, 1898). This paper is based upon the reports filed in connection 

 with the census of Michigan mollusca undertaken by the Concho- 

 logical Section of the Academy. A sketch of the plan of these re- 

 ports may be found in this journal for January, 1898. Of the 

 Unios, 7 or less than one-fifth, are known to range over the whole 

 State, 3 are characteristic of the northern portion, while 30, or 75%, 

 are confined to the southern portion of the State, and do not extend 

 north of the valleys of Grand and Saginaw Rivers. As no natural 

 barrier prevents the spread of these species northward, an explana- 

 tion is sought in the physical conditions of the region during the 

 glacial period, when the lakes drained into the Mississippi from the 

 southern end of Lake Michigan and into the Ohio from the western 

 end of Lake Erie. On the partial recession of the ice-sheet a chnu- 

 nel was formed across the State along the Saginaw-Grand valley. 

 " There can be no doubt that it was through these ancient channels 

 that the barren waters of the lake region were peopled by an immi- 

 gration of southern forms." A map illustrates the records of dis- 

 tribution of Unio luteolus, rubiginosus and Anodonta footiana. 



THE MOLLUSCA OF THE CHICAGO AREA : THE PELECYPODA, by 

 Frank Collins Baker, Chicago Academy of Sciences, Bull. no. iii. 

 This bulletin of 130 pages and 27 plates forms the first installment 



