THE NAUTILUS. 95 



Wabash basins to be by far the richest in species, the Lake Michigan 

 basin poorest, though with a good representation of LhnnceidcB. 



The catalogue is interesting and useful, though it would be better, 

 we think, if Dr. Call had followed modern classification, and had 

 adopted the rectifications regarding many species which have been 

 made in the last decade. He apparently thinks that progress in the 

 anatomical and systematic study of Mollusks abruptly stopped fifteen 

 or twenty years ago, as no innovations of later date are adopted, ex- 

 cept a few, mostly wrong, made by himself. Aside from these matters, 

 there are but few errors, and these not of grave consequence ; a fig- 

 ure of Strobilops is given for Zonites fulvus (p. 37G); Tebennophorus 

 dorsalis is said to be " the most common slug in Indiana," though we 

 think what he had was dark Agriolimax camjiestris. We note also 

 that the descriptions of Lamarck's Unios are quoted nut from the 

 original but from the Deshayes edition, and the accents of the French 

 remarks are badly ll balled up." — H. A. P. 



UnioniDjE of Indiana. — In Mr. Call's Descriptive Catalogue of 

 the Mollusca of Indiana, the author repudiates the attempt at a 

 natural classification of the LTnionida? made in Mr. Baker's Mollusca 

 of the Chicago Area, and cannot realize that such a system is pro- 

 posed seriously. He cannot understand why, for instance, such a 

 form as Unio trigonus is placed in the same subgenus as Unio plicatas. 



Now it is a fact that has been repeatedly demonstrated by Dr. 

 Lea's, Dr. Sterki's and my own observations of the anatomy of these 

 mollusks that Unio trigonus and the allied forms, the different species 

 of the Plicatus group, Unio pustulosus and its allies, JJnio coccineus, 

 U. subrotundus, U.kleinianus,axii\ the forms belonging to the Ghicia- 

 saivhensis group which have been placed in the genus Quadrula, all 

 have the embryos contained in all four of the gills, and when they 

 are thus filled they form thick, smooth pods. And there are certain 

 conchological characters which hold good in all these species. Their 

 shells are all solid, short, more or less inflated ; they generally have 

 a wide, flat hinge plate and almost invariably deep beak cavities. 

 Many specimens occur among species belonging to the Plicatus group 

 in which the plications are nearly or even wholly wanting, and the 

 epidermis varies from greenish to brown and black. Such specimens 

 are not far removed conchologically from the smoother forms of the 

 Pustulosus group or from U. sub/ "fundus and U. kirtlandianus. 



