THE NAUTILUS. O 



though the siphon is not recurved ; pillar smooth, nearly straight 

 with little callus; the body with no subsutural callus; the outer lip 

 slightly flaring, hardly thickened ; Ion. of shell 26, of aperture 15.5> 

 lat. 13.0 mm. 



San Pedro, Cal., in rather deep water, E. W. Roper; in whose 

 honor the shell is named. 



This is a singular species, recalling Ocinebra or Muritidea by its 

 surface sculpture and the constricted and appressed sutural region 

 of the whorls. I have not been able to find any species with similar 

 characters in the monographs or in the National Collection. It is 

 probable that it should be separated sectionally from the group 

 typified by F. coins, and it cannot be associated with Sipho or Chry- 

 sodomus, so it may be regarded as typifying a new section, Roperia. 



NEW UNIONIDJE. 



BY BERLIN H. WRIGHT. 



U. Strodeanus sp. nov. 



Shell smooth, subtriangular, not inflated, inequilateral, rounded 

 before, obtusely angular behind, slightly arched above and grace- 

 fully rounded beneath. Substance of the shell solid and nearly 

 uniform throughout. Beaks gracefully pointed, not prominent, 

 scarcely extending above the short red ligament and surrounded by 

 a few coarse, low undulations which do not extend back as much as 

 usual. Umbos flattened. Epidermis olive-black, rayless. Not 

 polished and with distant, faint marks of growth. Umbonial slope 

 obtusely angular or rounded ; posterior slope slightly compressed 

 and with two or three slightly impressed lines extending from beaks 

 to margin. Cardinal teeth strong, deeply cleft and inclined to be 

 direct. Lateral teeth prominent, curved and inclined to be double 

 in both valves. Shell cavity moderate and quite uniform. Beak 

 cavity slight and abruptly rounded. Cicatrices small, barely dis- 

 tinct and well impressed. Nacre white and only slightly iridescent 

 towards the margins. AVidth 2 in., length \\ in., diarn. 2 in. 



Habitat : Escambia River, West Flordia. 



Type in National Museum. 



Remarks: Affinity, U. reclusus nobis and U.simulans Lea. From 

 the former it differs in having a darker and rougher epidermis, not 

 so pointed behind, flatter sides, shorter and teeth heavier. From 



