THE NAUTILUS. 



Ill 



work, however, has been done in the Antoine or Little Mis- 

 souri rivers, while the Caddo and the upper Ouachita are al- 

 most unknown to the malacologist, and promise generous re- 

 muneration to whomsoever first will require their secrets. 



Although something like fifty species have been described 

 from Arkansas, 1 and the mountainous regions of northern, cen- 

 tral and western Arkansas have been often visited by concholo- 

 gists, the fauna of the low-lands, particularly the Unione fauna, 

 of the lower courses of all rivers, is practically unknown. Be- 

 fore a satisfactory catalogue of the Mollusca of the state can be 

 written, not less than forty counties call for a conchological 

 survey. 1 



A three year's pastorate in Arkadelphia, 2 the capital of Clark 

 County, gave the writer frequent opportunities for collecting 

 the mussels of Ouachita river and such land, and fresh-water 

 snails as were to be had. Through the kindness of Mr. George 

 H. Clapp the identification of the land shells has been made 

 nearly complete, and he has determined all of the rarer forms 

 here listed. Dr. A. E. Ortmann and Mr. L. S. Frierson have 

 been very generous in the help given on the Unios, but for the 

 most part this is the result of much patient study on the part 

 of Dr. Bryant Walker. Most of the specimens on which the 

 determination of the Unionidae depended are now in the Walker 

 collection. 



The country around Arkadelphia would be quite discouraging 



1 The richness of the Arkansas fauna is well indicated by a^comparison of 

 species described from this state and those described from the adjoining state, 

 Missouri, portions of each being included in the Ozarkian uplift. Exclusive 

 of the Unionidae, thirty-four species have been described from Arkansas, 

 twenty-three of which are land snails. From Missouri nine species and var- 

 ieties are listed, all of which with one exception, are fresh-water forms. 

 Consult : Simpson, " A Preliminary List of the Mollusca of Missouri," Proc. 

 Acad. Scien. St. Louis, Vol. XXII, No. 8, p. 68, and Pilsbry's Note in the 

 Nautilus, Vol. XXVIII, p. 12. This is especially significant in view of the 

 fact that the State of Missouri has been favored with the residence of faithful 

 and efficient conchologists, among whom may be mentioned Mr. Sampson, 

 and more recently Professor Utterback. 



2 From November 1910 to December 1913. 



