ORTMANN: monograph of the naiades of PENNSYLVANIA. 49 



River, West Virginia. Tlie shape was the same, as reported, but they were slightly 

 larger: 0.20 X 0.22 mm. I have repeatedly found specimens with eggs and with 

 distinct placentae; but when glochidia are present, the placentse easily fall apart. 



Breeding season: The specimen with glochidia was found on May 24, 1911, 

 and a specimen with eggs was collected on June 22, 1909. Other specimens with 

 eggs were received from Arkansas, collected on June 26, 1911. The early date for 

 glochidia is remarkable. It is astonishing, on the other hand, that among numerous 

 specimens collected on June 20, 21, and 22, 1911, in the Ohio River at St. Marys, 

 West Virginia, no gravid females were found. The species surcl.y is tachytictic; 

 Surber (1912, p. 7) gives May to July as the breeding season. 



Remarks: It is hardly possible to mistake this species on account of its marked 

 shape and sculpture. Yet there is quite a range of variation, chiefly with regard 

 to obesity of the shell, and to sculpture. As is seen in the measurements given 

 above, some shells are considerably more flattened, and it is to be noted that such 

 specimens are more frequent in the Allegheny than in the Ohio. This would 

 express the same tendency toward flattening of the shell in smaller rivers, which 

 we have noticed in several of the foregoing species. But in this case it is impossible 

 to distinguish a flat race, since there arc all intergrades, and only few flat indi- 

 viduals are found, always associated with others which are swollen (See PI. IV, 

 figs. 4, 5, 6). 



In the development of the tubercles we notice an important variation in which 

 the large tubercles of the posterior ridge are obliterated. Such specimens, which 

 at the same time were rather flat, have been described by Lea (Obs. IX, 1863) 

 as a separate species, Uiiio wardi (from Walhonding, Ohio; Wapsipinicon, Iowa; 

 and Coal River, West Virginia)."'^ Three specimens from the latter locality are 

 in the Carnegie Museum, derived from the Hartman collection. They undoubtedly 

 are the same specimens referred to by Lea, as being in the Hartman collection. 

 They agree very well with Lea's figure, but the posterior ridge is not entirely 

 smooth, although without the large tubercles. I have specimens hke these from 

 the Little Kanawha River and from the West Fork River. These also are remark- 

 ably flat. Finally specimens resembling these are sometimes found in western 

 Pennsylvania (See PI. IV, fig. 6). The second one, of which the measurements 

 are given (from Kelly), should be by all means regarded as wardi and there is a 

 half shell from the Monongahela at Charlcroi, which has been labeled by Simpson 

 as var. wardi, and rightlj' so. Compressed specimens, which also have the tubercles 

 more or less obliterated, have been found occasionally all the way down from the 



^' Lea says: "Coal River, Logan Co., Va.," but Coal River and Little Coal River are today in 

 Kanawha and Boone Cos., West Virginia. 



