EXPLANATION OF PLATES. 



Long lake is the head of the east branch of Fish river. Only a very 

 small part of this lake has been examined by me. Near the outlet several 

 species of shells were obtained, but not a single specimen of Limnasa. A 

 thoroughfare, one-half mile in length, connects it with Mud lake. In the 

 lower half of this thoroughfare Limnasa emarginata commences to appear 

 and is very abundant at the outlet in Mud lake. See plate 1 , fig. 1-10. 

 This is undoubtedly the original locality where Mr. Longfellow discovered 

 his specimens in 1842, and the name Limnasa (Radix) ampla was given 

 the shellsby Dr. 1. W. MiteheljJ' It is a very easy thing to name a speci- 

 men, but the criticism wilFcome after, and if the same name has been 

 used for a specie of the same family it must be changed. 



In 1842 Hartman published Limnasa (Gulnaria) ampla of Europe. 

 See plate 1 , fig. 18-19, drawn from specimens collected by A. S. Ober- 

 wimmer, Vienna, Austria. Some authorities claim L. ampla is only a 

 variety of Limnsea auricularia Linne also of Europe. See plate 1 , fig. 16- 

 17. Specimens from Elbe river, Germany. 



The best authorities agree that our shells are only a variety of Limnasa 

 emarginata Say, and W. G. Binney in Smithsonian jniscellaneous collec- 

 tion, land and fresh water shells of North America, part 11, 1865, in a foot 

 note proposes the name Mighelsi for the variety and this is generally 

 adopted. 



Plate Lfig. 11-15, is from the lower left-hand side of Mud lake. 

 The specimens in this lake are small, (eight-horn, colored, sometimes 

 ornamental, v/ith revolving bands; the color of this animal varies. The 

 specimens at the water edge are bluish-black or gray, and those in deep 

 wa'.er are very light and sometimes orange. Specimens are most com- 

 mon at low water mark, tOfc • miXox being about three feet in depth, gravel 

 botton, where they feed on Confervae, growing on the rocks. This shell is 

 a typical Limnasa emarginata Say. Dredging many places in this lake 

 from 3 to 13 feet not a single specimen of the above were obtained. On 

 the sand and gravel bars formed at the outlet in Cross lake a colony of 

 shells appear. ■ They are somewhat larger in size than those in Mud lake, 

 with a shorter spire and a wider aperture. See plate 2, fig. 1-6. These 

 specimens are very abundant some years. This summer in August, only 

 a few young shells could be found. The variety named mighelsi will be 

 found to correspond better to these shells than those found in Mud lake. 

 On the west side, about two miles south from the inlet at Cranberry Point 

 in two feet of water a colony of large specimens of the variety mighelsi 

 is found. See plate 2, fig. 7-11. Cross lake is 5 miles long and 1 1-2 

 miles wide. Few specimens have been dredged at the south end of this lake. 



Entering Square lake to the right is a large sand and gravel bar and 

 a large sheltered cove where Limnasa emarginata var. migelsi Binn., are, 

 some years, very abundant, attains the largest in size and the most variable 

 in forms of any known. See Plates 3-4. 



