ORTMANN: monograph of the naiades of PENNSYLVANIA. 293 



Hartman & Michener, 1874 (Schuylkill River, Chester Co.). 

 Dean, lS9r(West Branch Susquohantia River, Muncy, Lycoming Co.). 

 Pilsbry, 1S9-1 (Susquehanna River, York Furnace, York Co.). 

 Schick, 1895 (Delaware River, Pliiladelphia; Canal at Manayunk). 

 Ortmann, 19096, p. 204. 



Characters of the shell: Shell of about the same size and similar in shape to 

 that of L. luteola. Beak-sculpture also similar (Marshall, 1890, fig. 4), but valves 

 much more compressed. Epidermis yellowish, or light or dark green, more rarely 

 inclining to brownish, not smooth, but roughened by close concentric wrinkles. 

 Dark green or blackish rays are generally present, but they are not well-defined, 

 except that in light-colored specimens they are sharper. Concentric bands of 

 lighter and darker color are often present. 



Hinge similar to that of L. luteola, as well as the rest of the inside of the shell, 

 but the color of the nacre is more variable, sometimes being entirely white, often 

 tinted with pinkish or salmon, and even entirely of these colors. 



Sexual differences of the shell much less marked than in L. luteola. The female 

 shell has a similar tendency to expand in the postbasal region, but only slightly, 

 and never so distinctly as in L. luteola. Some females are even hard to distinguish 

 from males. 



L. H. D. 



Size: 1. Manayunk, Cat. No. 61.4051 (probably d') 93 mm. 5.3 mm. 27 mm. 



2. do. Cat. No. 61.1789 (9) 88 " 52 " 28 " 



3. Tunkhannock, Cat. No. 61.4054 (gravid 9 ) 87 " 49 " 29 " 



4. Yardley, Cat. No. 61.3473 (probably d') 71 " 42 " 21 " 



5. Selinsgrove, Cat. No. 61.4868 (cf) 70 " 40 " 23 " 



6. South Waverly, Cat. No. 61.4053 ( 9 ) 60 " 34 " 17 " 



Soft parts (See Ortmann, 1912, p. 349) figured by Lea (Obs. II, 1838, PI. 15, 

 figs. 48, 49). Glochidia (See Lea, Obs. VI, 1858, PI. 5, fig. 20). I observed them 

 in a specimen from Severn River, Ontario. They agi'ee with those of L. luteola: 

 L. 0.22 to 0.23, H. 0.27 to 0.28 mm. 



Breeding season: According to Conner (1907) "all the year round." I have 

 taken a gTavid female with eggs on Aug. 22, 1909. This would mdicate the begin- 

 ning of the season. The female with glochidia was collected Aug. 20, 1914. It 

 might be that this represents the end of the breeduag season, which thus would 

 overlap with the next one. 



are both probably females, which is seen at once by the general outline of the shell. It is remarkable, 

 that this mistake of DeKay has never been discovered, although his error with reference to his Unio 

 radintus (which is Eurynia iris novi-eboraci) has been corrected previously. There is no doubt that the 

 confusion within the two species, radiata and ochracea, is in large part due to these incorrectly named 

 figures of DeKay. 



