156 Cincinnati Society of Natural Hiiitory. 



4. Number of cletbrinities of peristome, 11. 



5. " " " " under surface, 12. 



6. " " " causing open urnbilicus, 2. 



7. " " " " double peristome, 2. 



8. " " '' " dwarf specimens, 2. 



Under the first case the deformities consist of a depression of the 

 spire, in some cases, and its unnatural elevation in others, caused by 

 the crowding together of the whorls. In a few specimens, the center 

 of the spire is depressed below the plane of the bod\--whorl. In such 

 cases theinjurj' to the shell occurred at a very earlj' period, retarding 

 the growth of the incipient whoi-ls. After recovery, the healthy growth 

 of suceeding whorls overtops the spire. Damage occurring to the fourth 

 whorl has caused the downward growth of the fifth, elevating the spire 

 abnormally, and throwing the last suture below tiie central line of its 

 whorl in the region of the aperture. This case is not uncommon, and 

 the abnormal form arising from it seems to be perpetuated. In many 

 instances the spire has been roughened, and the whorls abnormally an- 

 gulated at certain points, damage from which they have entirely re- 

 covered further along in their growth. 



Under the second case, the deformities consist of the abnormal 

 depression of the umbilical region or the reverse. A prevention of the 

 reflection of the peristome over the umbilicus, leaving it entirely open 

 in two cases, and partial elevation of its edge in othei'fe, though not 

 enough to expose the aperture. 



Under the third case, the deformities consist of the abnormal thick- 

 ening and roughening of the lip; of undue sinuosities; and of doubling 

 in the two cases tabulated above. This thickening, in many^ cases, 

 causes callosities on the lower third of the peristome, near the umbilical 

 region. In the normal condition of the shell there is a lamellar tooth 

 on this part of the peristome, which, being irregnlarlj- deposited, gives 

 rise to the deformit\' mentioned. This case, also, seems to be perpet- 

 uated, and to have given rise to a wide spread variety, familiar to all 

 students of this species. The fourth case is the result of the first and 

 tliird. Abnormal elevation or depression of the spire, causing an un- 

 natural angle of the terminal whorl, together with a sinuous peristome, 

 have given rise to many curious forms of aperture. Thus, it is some- 

 times A^er}' unnaturally lengthened horizontallj- and depressed verticalh' ; 

 sometimes very much elongated vertically, and correspondingly 

 shortened in the opposite direction. Tiie angle at which the outer 

 plane of that portion of the peristome above the aperture meets that 

 below, varies from a right to a very acute one. These causes give 

 rise to a very great variety of forms in the aperture. 



Under number five the injuries have been such as alread}- stated in 



