F882.J Zoology. 401 



tidoe first appear in New York, and are almost confined to the 

 district occupied by the Unionidae just mentioned. They do not 

 cross the Mississippi, and are chiefly found in mountain streams." 

 Now, this last statement, " they do not cross the Mississippi," 

 does injustice to what Professor Wetherby really states in the 

 paper reviewed, and does violence to the facts in the case. The 

 statement made by the author reviewed is " This fauna [Fauna CJ 

 has a very limited distribution of genera and species west of the 

 Mississippi * * ." (See Am. Jour, of Sciences, March, 1882, 

 page 207.) Mr. Tryon, in his generally excellent monograph of 

 the Strepomatidas published as No. 253 of the Smithsonian Mis- 

 cellaneous Collections (1873), made the same statement the writer 

 in the Naturalist made, but with reference solely to the Trypa- 

 nostomoid division of that family; he recognizes the occurrence 

 of Goniobasis in various streams west of the Mississippi and trib- 

 utary to it, and also the few forms of doubtful generic relationship 

 from California and Oregon (Op. Cit.,pp. xxxviii, xl, xli, xlvii, 

 and xlviii). Of the genus Goniobasis there are seven forms 

 from west of the Mississippi exclusive of those found on 

 the Pacific slope. They are Gon. cubicoides Gon. potosiensis, 

 Gon. sordida, Gon. lirescens, Gon. ovoidea, Gon. haleiana, and 

 Gon. alexandrensis. I am not aware that Gon. cubicoides Anth. 

 has been hitherto reported from any other habitat than Indiana; 

 but the specimens to which reference is here made can be referred 

 only to that species, with any degree of certainty. I obtained 

 them from the Middle Raccoon river, Dallas county, Iowa, and 

 have distributed them among some of my correspondents with 

 labels as above. Of Trypanosoma, one species at least occurs 

 west of the Mississippi — the Try.subulara Lea — which I desire to 

 place on record here. Several hundred specimens were taken 

 from the Des Moines river, at Fort Dodge, Webster county, 

 Iowa, by the writer, many of which have likewise been distributed. 

 They occur further to the westward, since five species of this 

 family are accredited to Nebraska by Professor Aughey (Sketches 

 of the Physical Geography and Geology of Nebraska, page 144), 

 but specific names are not given ; these latter, however, may be 

 found in Bulletin U. S. Geological Survey, Vol. in, No. 3, to 

 which I have not access at this writing. The streams of the 

 western slope of the great basin of the Mississippi have not yet been 

 examined with sufficient care to justify any statement as to their 

 wealth in Strepotnatida, but such evidence as is now accessible 

 Points to the conclusions reached by Professor Wetherby. 



In the paper by Professor Wetherby (Am. Jour of Science, 

 March, 1882, p. 208), occurs a most singular error in a matter of 

 fact, which would seem to have an important bearing on the par- 

 ticular theme in connection with which the statement is made. 

 Referring to the somewhat anomalous distribution of Matgaritana 

 nargaritifera Linne, he states that the species is found " in Maine 



