159] FAUNA OF BIG VERMILION RIVER— BAKER 61 



wide and not exceeding six inches in depth. The bottom was of mud and 

 fine sand. The largest specimen measures 7 mm. in length. This spe- 

 cies was not collected from streams flowing into the Big Vermilion River. 



50. Amnicola limosa (Say). 



This common Amnicola occurred at three stations, only two of these 

 yielding living specimens. At the station above the iron bridge north of 

 Sidney, the shells were secured by sweeping the vegetation bordering the 

 shore with the Walker dredge. The limosa from the Salt Fork are rather 

 corpulent but are not as globular as the variety known as porata (Say). It 

 is noteworthy that this species (and in fact the genus) should be found only 

 in a stretch of the stream three miles in length, from 16 to 19 miles below 

 Urbana. None were seen below the dam. Individuals were rare and 

 difficult to find. Near the cement bridge east of Sidney, dead shells 

 occurred among water plants {Nymphaea advena) but no living specimens 

 could be found. Limosa was not collected at the stations in the San- 

 gamon River. 



51. Amnicola (Cincinnatia) cincinnatiensis (Anthony). 



This Amnicola occurred rarely, but living, at but two stations in the 

 Salt Fork, 16 and 17 miles below Urbana. The largest and only adult 

 individual collected measures 6 mm. in length. Several half-grown shells 

 were found. About two years ago Mr. James Zetek found cincinnatiensis 

 near St. Joseph. A careful search of this region, both in the Salt Fork 

 and in the small streams flowing into Salt Fork, failed to produce a single 

 specimen of this species. During the intervening ten years the species 

 appears to have died out, either from the effect of sewage pollution or 

 from some other unknown cause. 



FAMILY VIVIPARIDAE 



52. Campeloma rufum (Haldeman). 



The Campelomas of the Big Vermilion all appear to be referable to 

 Haldeman's rufum. The shell is more or less pinkish, especially on 

 the spire. One specimen from the iron bridge north of Sidney resembles 

 Haldeman's figure 1 on plate 3 of the Monograph, which is the type 

 of rufum. Specimens from Homer Park, below the dam, are strongly 

 suggestive of integrum (Say), many of the individual shells being like 

 Binney's figure 96 which represents Say's integrum. With these are 

 short-spired shells recalling the obesum of Lewis as figured by Binney 

 (figure 95). These are not quite like the figures of Lewis (1875, pi. 23, 

 figs. 4-5) which are rather broader. Variation in rufum seems to parallel 

 that of integrum in the length of the spire. Typical integrum has a white 

 aperture and a bright green shell devoid of the peculiar pink tint of rufum. 



