No. 2.] SNAILS OF THE GENUS 10— ADAMS. 59 



Nolichucky. This is the only stream which is uniform in this respect and contains only one kind 

 of young shells. 



Immature live shells were found in the NoHchucky at only one locality, and that was near 

 the mouth of the river, lot 104. This series is fortunately very complete, containing specimens 

 from those of class 1 on to the fully mature, plate 48. They were collected in October. This 

 is the only series of very yoimg lo which is comparable with lot 51 from Clinch Kiver, in the 

 extent of the series of very young shells. In these shells, all the whorls are carinated, with the 

 exception of the minute apical embryonic one. The second, third, and fourth, and in some 

 cases the fifth whorl, do not possess spines or undulations. There are 7 whorls in the youngest 

 shells, and they average slightly larger than those in lot 51 from the Clinch. The first six whorls 

 at least are probably embryonic. The spines themselves are variable, distinctly carinated, 

 corrugated, and green in color, and are variable in carination, plate 5, figures 16-25. These 

 young shells stand in marked contrast with those of lot 51 ; they agree in the carination of the 

 whorls, and lack of spines on the extreme apical or embryonic whorls, but beyond this stage 

 there are radical differences. It should be recalled that the young of lot 51, in all probability, 

 contains young of both the smooth and spinose shells of the Cliach River, the younger stages 

 of which are both smooth or faintly undulated, in marked contrast with those of lot 104, which 

 are strongly spinose. 



A young shell, lot 182, was found near the mouth of the Nohchucky in the French Broad. 

 This was in the class 3 stage, and clearly of the Nohchucky type. Yoimg shells from the lower 

 French Broad are exceedingly limited in number. One shell, class 3, lot 136, plate 5, figure 

 26, from Dandridge, Term., was smooth until class 3 was reached, and then spines were devel- 

 oped, not like those of the Nohchucky, but more like those of the shells in the upper parts of the 

 Tennessee River proper and in the lower Holston. A second specimen, figure 27, developed 

 traces of spines at class 2 stage. Other shells, somewhat smaller but of the same type (i. e., 

 smooth at apex and spiny later), were found at Hanging Rock Shoal, lot 137, plate 5, figure 31, 

 and at the Seven Islands Shoals, lot 156, plate 5, figures 32-36. It is important to note the con- 

 trast in the character of these young shells and those found in the Nohchucky. Among the 

 shells from Dandridge, lot 136, there are a few individuals of about class 3 stage which appear 

 to be mature on account of the heaviness of the shells, plate 5, figures 28-30. They are different 

 in appearance from other mature shells, and are the form angitremoides. The apical whorls of 

 this form appear spiny. These shells are evidently more closely related to the spinose Nohchucky 

 shells than to those with smooth apices during the classes 1 and 2 stage. Others from lot 124, 

 from near Knoxville, plate 5, figures 44-48, are also of this form. 



Tennessee Biver. — A series of young shells from Dickinsons Island, lot 47, from near the 

 headwaters of the Tennessee River proper, contain shells of classes 2 and 3, with smooth apices, 

 but the last whorl may be smooth or spinose, plate 5, figures 37-43. Almost all of the shells 

 in the class 2 stage possess some carina, traces of nodules, or spines. These are the young of 

 loudonensis. 



The shells from Looneys Island, lot 124, angitremoides, appear to be a dwarfed variety, 

 plate 5, figures 44-48. This lot contains only a very few which, from their smaller size, appear 

 immature; these belong perhaps to class 3. As very young shells are lacking, and the apical 

 whorls are eroded, the proportion of shells having smooth or spiny apices can not be definitely 

 determined. But judging from the pits formed by erosion, which generally mark the position 

 of a spine, it appears that a great majority of the shells are spinose, nearly to the apex. One 

 individual was found which reached the class 2 stage as a smooth ( ?) shell, and then became 

 spinose, plate 5, figure 45. There is considerable overlapping of whorls and this tends to obscure 

 the degree of spinosity. 



Lot 101, from Lyon Shoal, contains only a few of the very immature individuals. These 

 are all very spiny and are thin shelled, when contrasted with those of the angitremoides form 

 of lot 124. They occur only about 2 miles farther upstream. A larger series from the above 

 locahty, lot 100, contains young belonging to or approaching class 2. These j^oung vary much; 

 at the class 1 stage some were spiny and others were smooth, developing spines only as class 3 



