126 



AMERICAN JOURNAL 



Of course, where the rivers alone form the bounderies, many 

 of their species have spread into the adjacent streams; but in 

 East Tennessee, Southwest Virginia, West North Carolina and 

 Northwest Georgia, where several parallel mountain ranges 

 completely enclose the valleys of the rivers, almost all the 

 species inhabiting them appear to be confined within their 

 limits. And here, a space of one hundred and fifty miles in 

 leno-th, by fifty in breadth, will cover the territory occupied 

 by probably more than a hundred and fifty species of Strepo- 

 matidse. 



The following table, representing the arrangement of the 

 Strepomatidx followed in my " Synonymy" of the species, pub- 

 lished in the Proceedings of the Academy of Natural Sciences, 

 1863-4, will show both the total number of species, and the 

 absolute and relative strength of the genera. A few species 

 since published have not all been included, as we are not 

 sufficiently well acquainted with them : — 



12 



8 

 2 



15 

 32 



Number of Species 

 1. Tnjpanostomoid Section. 

 10, 5 



smooth, 2 



spinose, 3 



PLEUROCERA, 84 



tuberculate, 7 



sulcate, 



striate, angulate, 

 carinate, 

 plicate, 



smooth, angulate, 

 " not " 



ANGITREMA, 12 



with a coronal of tu- 

 bercles, 4 

 with two rows of tu- 

 bercles, 1 

 with a central rovr of 

 tubercles, 7 



LITHASIA, 17 



large, oval, inflated, o 

 small, compact, 7 



obliquely flattened, 2 

 subcylindrical, 3 



STREPHOBASIS, 8 



ovate conical, 3 



cylindrical, 6 



OF Strepomatid^. 



2. Goniohasic Section. 



EURYC^LON, 6 



GONIOBASIS, 274 



spirally ridged, 1 



tuberculate, ' 18 



plicate, 85 



angulate, 16 



bi-multi-angulate, 11 

 carinate, 4 



smooth, short, 26 



elevated, 43 

 striate '' 8 



compact, ponderous, 62 



SCHIZOSTOMA, 26 



fissure narrovv', 14 



fissure wide, 12 



MESESCHIZA, 1 



