THK NAUTILUS. 5 



respect, and specimens were found in places where the marl was less 

 abundant, which seem to connect the two forms. 



Along the Lake Michigan shore, among the stones, Physa om-,7- 

 laria Say occurred, exhibiting a very heavy, solid, opaque shell. 

 The same form is found plentifully at Mackinac Island, and seems 

 to be one of the most characteristic forms of the region. A heavy 

 malleated form of Limncea emarginata Bay is associated with it in 

 both localities. Limnrca desidiosa Say and Physa Integra Hald. 

 were found plentifully in similar localities. 



In one of the smaller inland lakes near Charlevoix, the dark red 

 form of Planorbis e.cacuttts Say, recently distinguished as var. ru- 

 bellus by Sterki, was found. The typical form of the same species, 

 as well as P. bicuriiiiitiis Say :\\nl parvtts Say, occurred abundantly 

 in the deep-water dredging at High Island. The great similarity 

 of the Limnreid fauna of northern Michigan to that of Maine was 

 again manifested in the discovery, in a small mill-pond near Charle- 

 voix, of the ecarinate form of P. bicarinatus recently distinguished 

 by Mr. Pilsbry as var. aroostookensis. The only species of Ancylus 

 met with was the A. parallel ns Hald., which was common among the 

 lily-pads in all the smaller lakes. Among the operculates there was 

 little of special interest. Goniobasis livescens Mke., as usual in the 

 lake region, was abundant everywhere, and in Lake Michigan was 

 found in thirty feet of water. Valvata tricarinata Say and sincera 

 Say were also abundant in deep water, and the latter species from 

 High Island was unusually large and fine, and might be referred to 

 the form described as V. striatu, by Lewis. The Campolomae were 

 also abundant. The slender northern form described by Lea as C. 

 milesH, however, was found only in one lake on Beaver Island. The 

 Lake Michigan form was C. decisa Say. The Amnicolae were ex- 

 ceedingly abundant, the two larger forms A. Ihnosu Say and litstrica 

 Pils. occurring everywhere. -4. grana Say was found at High 

 Island only, as was also a single specimen of Bythinella oblnsa Lea. 

 One of the few disappointments met with was the failure to find the 

 deep water form, A. sJteldoni Pils., originally found in the deep 

 water of Lake Michigan, at Racine, Wis. The only novelty among 

 the Unionidae was the occurrence of Unio borealis Gray, in a small 

 lake on Beaver Island. This is another addition to our fauna, and, 

 I believe, the most western locality yet cited for the species, which, 

 as Mr. C. T. Simpson, to whom I am indebted for the identification, 

 suggests, is apparently only a form of Unio litteo/ns Lam. The 



