44 MUSSEL FAUNA OF MAUMEE EIVER. 



was 20. The Maiimee specimens are brightly polished and can be 

 distinguished by this feature from the rest of the summer's collection. 

 This is an exceedingly handsome shell, but of no commercial im- 

 portance, as both its small size and peculiar form are disadvan- 

 tageous. The nacre, though usually white, is occasionally of a 

 beautiful warm pink. 



9. Unio gihhosus (Barnes). Spike. Unio gibhosus was fairly com- 

 mon the whole length of the river. It is one of the species of wide 

 distribution and considerable variability. Our specimens do not 

 exhibit much variation, however. Most were of the solid, short- 

 ened, somewhat humped type. The long examples, which have pro- 

 cured for the species the name " spike," sometimes closely re- 

 semble Lmnpsilis rectus^ from which they can be distinguished by 

 the sculpture of the umbones and by the shape of the lateral teeth, 

 while the short humped form is frequently almost indistinguishable* 

 from Ptychohranchus jjhaseolus; about the only way to tell them 

 apart is by observing the color and texture of the epidermis, that 

 of U. gibhosus usually being darker, and by the shape of the body 

 cavity. One shell was found in the St. Marys, two in the St. Joseph 

 near its mouth, and three in the Maumee near Fort Wayne. It was 

 most abundant in the central portion of the river from Maumee 

 Center Bridge to the bridge at Florida, Ohio, and was common in 

 the Auglaize River. Lower down the Maumee it gradually disap- 

 peared, the last few shells having been seen at Grand Rapids, Ohio, 

 below the dam. In all, 63 shells were obtained in the Maumee Basin. 

 It appears to be one of the common shells in Lake Erie, 16 having 

 been found on the shore of Put-in Bay Island. Both purple and 

 white nacred forms were present. The greater number, about two- 

 thirds, had white nacre, one had rosy nacre, one had purple nacre, 

 white at the edges, and the others were intermediate between white 

 and purple. Young examples showed delicate rays. 



This species is of no commercial value, as even the white forms 

 have the nacre quite dull. In some localities the distomid of Kelly, 

 associated with dorsal baroques, is a common parasite, but they are 

 not abundant in the Maumee. 



10. Alasmidonta truncata (B. H. Wright). This is not an espe- 

 cially common shell in the Maumee Basin. According to Simpson" 

 it is a Mississippi Valley species which has migrated into the upper 

 parts of the St. Lawrence Basin. It is rather variable in form and 

 is sometimes difficult to distinguish from Strophitiis edentulus. It 

 was found in the feeder canal and St. Joseph River at Fort Wayne. 

 Occasional examples were encountered along the course of the river, 

 as 2 at Kern Reservation, 1 at Maumee Center Bridge, 1 at Ant- 

 werp, Ohio. Three large ones were obtained in the Auglaize River 



» Synopsis of the Naiades, Proceedings U. S. National Museum, vol. xxii^ p. 671. 



