J 26 MOLLUSCA. 



abundant in the mountains occur rarely, or not at all, in the latter 

 section, and the converse is also, in a measure, true. Indeed, several 

 genera, or subgenera, of each region are unrepresented in the other. 

 Twenty-one species of land, and two of fresh-water mollusks which 

 were collected, are named as follows by Mr. Henry Prime of River- 

 dale : 



Macrocyclis concava Say, P. striatdla Anth,, 



Zoniics f?ilignios2is Griff., Tebennophorus Carolinensis Bosc, 



ligeriis Say, Helicodiscus lineatus Say, 



inornatiis Say, Pallifera dor salts Binn., 



arbor CHS Say, Stenotrenia nionodon Rack., and 



indent at lis Say, var. fraterna, 



minusculus Binn. (?).'=' Mesodon albolabrts Say, 

 Binneyaniis Morse, " dcntifera Binn., 



exigujis Stimpson, " Sayii Binn., 



fiilvus Drap., Succinea obit qua Say, 



inulttdentattis Binn., Physa heterostropha Say, 



Patula alternata Say, Anodon Benedicitt Lea. 



This collection was made without systematic or extended search, 

 and, though it is to be considered as reasonably representative of the 

 immediate localities explored, must necessarily be too imperfect for a 

 broader application. 



Although justice cannot here be done to the Flora of the region it 

 should not be passed over without some allusion to its decidedly 

 Canadian characteristics. These, and the abrupt physiographical 

 changes from contiguous regions which they represent, cannot be 

 more clearly brought out than by comparison, and to this end the 

 Flora of the vicinity of my own home at Riverdale-on-Hudson may 

 be considered in counterview. The Flora of this section may be 

 regarded as fairly representative of that of the Hudson \ alley for 

 some distance above New York City, and is far less southern in 

 character than that of the coast region of New York and New Jersey, 



Specimen too fragmentary for positive identification. 



