66 THE NAUTILUS. 



it. Its general form, texture and color of epidermis inclines me to 

 believe that it is a Strophitus, related to S. tombigbeensis. I find 

 some vestiges of plication on one or two specimens of Strophitus in 

 our collection. The teeth of this are stronger than in any specimen 

 of that genus I have seen, but there is much variation in this matter." 

 I take great pleasure in naming this species after Mr. B. H. 

 Wright, who has done so much in recent years in developing our 

 knowledge of the Unionidse of the southern states. 



NEW PISIDIA. 



BY DR. V. STERKI. 



The following Pisidia have been known as distinct species for sev- 

 eral years, and the names have been used in my own collection as 

 well as in identifying specimens sent for examination by many con- 

 chologists. So they should have been published long ago. 



Pisidium affine n. sp. Rather large, well-inflated, slightly oblique, 

 beaks somewhat posterior, large and prominent in full-grown, broad 

 and quite low in young specimens, rounded or slightly flattened on 

 top ; superior and inferior margins moderately curved, posterior sub- 

 truncate, with slightly marked angles above and below, supero- 

 anterior forming one regular curve from the beaks to the anterior 

 end, which is low-situated and well-rounded ; surface distinctly and 

 somewhat irregularly striated, with some coarser lines of growth, dull 

 or somewhat shining ; color lighter or darker grayish horn to plum- 

 beous or brownish with a few irregular darker zones corresponding 

 with the lines of growth, and often with fine darker mottlings, usually 

 with a broad lighter zone along the margins; the young are pale 

 horn or straw-colored ; shell moderately thick, nacre whitish, muscle 

 insertions little ; hinge rather stout, plate rather broad ; cardinal 

 teeth long, not very strong, the right one curved, its free edge often 

 indented in the middle, its posterior end somewhat thicker, with a 

 fine groove, the left anterior tooth curved, the posterior slightly so, 

 oblique, rather behind the anterior, each covering the other for half 

 their lengths ; lateral teeth stout, rather long, their cusps short and 

 somewhat pointed, the outer ones in the right valve of good size; 

 ligament rather long and stout. 



Size : Long. 6, alt. 5, diam. 4 mill, (average). 



