ORTMANN: monograph of the naiades of PENNSYLVANIA. Ill 



Characters of the shell: Shell rather small and not heavy. Outline elongated 

 trapezoidal, or elongated ovate, lance-head shaped, a little over twice as long as 

 high. Greatest height of the shell about in the middle at the ligament (mostly 

 height of shell about the same from the beaks to the end of the ligament) . Anterior 

 end rounded, posterior end tapering and bluntly pointed. Lower margin more or 

 less curved, but often almost straight in the middle. Upper margin straight or 

 somewhat curved, nearly parallel to the lower margin, and forming a more or less 

 distinct angle with the upper posterior margin. Beaks not prominent, placed 

 rather anteriorly, but at a certain distance from the anterior end. Beak-sculpture 

 identical with that of E. violaceus, but sometimes the straight portion of the bars, 

 in their middle part, is shghtly and indistinctly sinuated. Shell not swollen, more 

 or less compressed, with the sides of the disk rather flat. A rounded, indistinct 

 posterior ridge is present. Surface without sculpture. 



Epidermis greenish olive, brownish olive, yellowish brown to brown, or even 

 blackish. Young specimens sometimes with rather indistinct, greenish rays, of 

 the same character as those of E. violaceus, but in most cases no traces of rays 

 are visible. Growth-rests generally not marked off by darker color. 



Hinge-teeth well-developed, but not very strong, of the general character of 

 those of E. violaceus. Beak-cavity shallow. Dorsal muscle-scars in the beak- 

 cavity. Nacre whitish, lurid, or of some shade of red or purple, lighter or darker, 

 often with coppery iridescence. 



No sexual differences in the shell. 



L. H. D. 



Size: 1. Romney, Cat. No. 61.5898 (extralimital) 88 mm. 38 mm. 23 mm. 



2. Fulton Co., Cat. No. 61.4323 (largest from Pa.) . .70 " 30 " 15 " 



3. do. do 66 " 30 " 16 " 



4. do. do 60 " 27 " 16 " 



5. do. do. 49 " 23 " 11 " 



Soft parts (See Ortmann, 1912, p. 270). Gravid females have subsequently 

 been found, and the structure of the marsupium agrees fully with that of E. violaceus. 

 Glochidia: L. 0.20, H. 0.20 mm., similar in shape to those of E. violaceus (which 

 are 0.20 X 0.19 mm.). 



Breeding season: Gravid females were found on May 6, 1912; June 3, 1912; 

 June 4, 1912; June 7, 1912; June 8, 1912. All these were from the Potomac, 

 Rappahannock, and James drainages, outside of Pennsylvania. At the earliest 

 date, glochidia in some individuals were already present. 



Remarks: Obliquaria cuprea Rafinesque (1820, p. 304) is this species, as is 

 evident from the description, the very poor (exaggerated) figure, and the comparison 



