554 KANSAS CITY REVIEW OF SCIENCE. 



have been identified by different conchologists as the variety hildrethiana, Lea, but 

 they w^ere evidently the mature form of others which all identify as gyrina. The 

 smaller ones were sixteen mm in length, of six whorls and entire apex. 



37. Fhysa heterostrophe, Say. — In no two streams are these shells exactly 

 alike. In some the shell is clear and pellucid; in others quite black. Again at 

 some seasons of the year they will be pellucid and at others black. The size and 

 the shape vary almost as much as the color, and while it is the most common species 

 of the genus, conchological authorities do not agree in their identifications, even as 

 between this and the preceding species. The same process that would make 

 Stenotremi monodon and S. leaii one species, would also make these one. 



38 Planorbis trivolois, Say. — Of this common species there are two va- 

 rieties found. One is about thirteen mm in diameter and the other eighteen mm. 

 The first is more uniformly with basal portion of the labrum horizontally subrec- 

 tihnear, and not extending below the level of the base, though this is not the case 

 with all, and a part of the larger variety are of that form. 



39. Planorbis bicarhiatus, Say. — Not very common. 



40. Planorbis parvus, Say. — In November, 1882, I found this species for 

 the first time, and then got only a few specimens from a pond on Flat Creek. 



41. Planorbis . — From Flat Creek I obtained a couple of young 



shells, between one and two mm in diameter. They do not seem to belong to 

 any of the species before named, and I have not yet been able to identify them. 



42. Ancylus tardus^ Say. — Fine-specimens of a reddish color. 



43. Melantho integer, Say.^ — Common. 



44 Amnicola poraia, Say. — In the summer of 1881, when the streams were 

 very low, this was obtained in large numbers. 



45. Amnicola orbictilata, Lea. — This very rare shell was obtained in small 

 numbers with the preceding. 



46. Goniobasis cubicoides, Anth. — This was found in small numbers at one 

 place in 1881, but during the past year with diligent searching, I could not find any. 



47. Sphcereum partumtium, Say. — Plenty. 



48. Sphcereum striatinum, l^diva. — Plenty and typical. 



49. Sphcereum stamineum, Cour. — Rare. Has been found only on Little 

 Muddy. 



50. Pisidium variabile, Prime. — Not plenty. 



51. Pisidium compressum, Prime. — A few were found in 1881, but the same 

 locality in 1882 did not furnish any. 



As the Unios in all our streams are too much eroded to make good cabinet 

 specimens, I have not made an effort to get a full collection of them, and will 

 not now give a partial list. The number of species here given is not equal to 

 those in many local catalogues having a similar fauna, but in some of these latter 

 I have noticed some very doubtful identifications, such as locating a West India 

 species in one of the northwestern States. When necessary corrections shall have 

 been made in each of the lists, the number here will probably be found about the 

 average of more northern localities, with a somewhat larger number of rare species. 



