118 
M0LLU8CA. 
Some notes on perforating Mollusks by W. 0. Macintosh, Ann.N. H. 
(4) xiii. pp. 344 & 345. 
The influence of granitic soil on the shell of Mollusks is discussed ; 
not only Margaritana margaritifera^ but also Unio batavus, Neritina, and 
Lithoglyphus, have a very thick and much eroded shell, but Ancylus is 
unusually thin in the streams of the granitic part of South Eastern 
Bavaria; S. Clessin, Nachr. mal. Ges. 1874, pp. 87-89. 
Balea perversa Cionella luhrica active on 20th January, at Kiel; 
W. Fack, Schr. Ver. Schlesw. Holst, i. pp. 277 & 278. ' 
Stenogyra martensi (Strobel) survived immersion in water for 48 hours; 
Strobel, Malac. Ai’gent. p. 29. 
Observations on freshwater Mollusks in infected water, by GiIirardin, 
J. de Conch, xxii. p. 332 ; Cyclas, Pisidium, and Planorhis corneus resist 
its effects more than Limncea. 
Teratology, 
S. Clessin (JB. Ver. Augsb. xxii. pp. 23-107) has published a treatise 
on the deformities of Mollusks and their shells, in which he has collected 
a large amount of observations, made by himself and others (chiefly Porro, 
Hartmann, and Moquin-Tandon) ; he takes rather a wide view of the 
subject, including, for example, the variations in the bands of many 
species of Helix. He classes the single cases in the following manner : — 
I. Monstrosities : changes in shape of considerable amount, limited to 
' the animal. They are caused — 
1. By the individual disposition of the animal, p. 34. 
2. By injury from without, mutilations, p. 36. 
II. Modifications : changes in the shell caused by affections of the 
living organs from without. 
a. Founded more particularly on the individuality of the animal. 
1. Difference of colour, p. 39. 
2. Difference or want of bands, p. 52. 
3. Want of colour, albinism, p. 45, and as a smaller degree of it 
the pale green colour of some varieties of Hyalina^ p. 49. 
4. Perversity of whorls, p. 68. 
b. Founded more particularly on external circumstances. 
5. Thinness or thickness of the shells, the latter often caused by 
abundance of calcareous matter in the soil, p. 72. 
6. Wcathor-boaton or decaying shells. 
7. Overgrowth of shells, p. 75. 
in. Anomalies : deformities of shell by mechanical injury not affecting 
the animal. 
1. Erosion of the shell, p. 78. 
2. Injury to the shell by shock or fracture, p. 82, sometimes re- 
sulting in — 
a. Lengthening of the spire or scalar form, p. 90. 
h. Abbreviation of the spire, p. 100. 
c. Displacement of the spire, p. 101. 
A scalar form of Planorhis complanatus described by Pir]6, Ann. 
Mal. Belg. vi. pis. hi. & iv. 
