8 Moll 
MOLLUSCA. 
also the existence of a vascular system as indicated by Leydig in the 
embryo ; he also treats upon the supposed “phylogeny ” of the Mollusca. 
Z. wiss. Zool. xxvi. pp. 414-433. 
E. Ray Lankester maintains the correctness of his observations 
against Fol, Iheriug, Rabl, and Bobretzky, adding some new, upon the . 
embryology of Cyclas, which develops the shell-gland at an early 
period in comparison with Pisidium, and upon the Gastrula-stage in 
Limnceus. According to him, the blastopore does not become the per- 
manent mouth, either in Limnceus or in Paludina : in the former, it is 
closed, or nearly so, in the further course of development ; in the latter, 
it is transformed into the anus. Q. J. Micr. Sci. (2) xvi. pp. 320-327, 
& 377-385, pis. xxiv. & xxv. [see also Ann. N. H. (4) xviii. p. 77]. 
The development of the jaw and radula in very young animals before 
and after hatching, has been observed by F. Wiegmann [son of the well- 
known herpetologist, who died in 1840], in various species of Arion^ 
Limax, Helix, Vitrina, and Pupa. The median tooth is always wanting 
in the first rows of the radula, and the jaw is at first manifestly com- 
posed of two lateral parts which afterwards become united in the median 
line. Numerous measurements show the relative growth in the various 
species. JB. mal. Ges. iii. pp. 193-235, pis. v. & vi. 
AnomaMes and liestoration of Parts, 
A scalarid specimen of Helix aspersa observed to have frequently 
broken the extremity of its spire, and to have formed an internal 
septum, just as Bidimus {^Stenogyra'] decollatus does normally ; the liver 
was much diminished. In one instance, the animal was entirely denuded 
by accident, and, after the shell was replaced, it survived. P. Lataste, 
J. de Conch, xxiv. pp. 242-246. 
Helix pomatia restores the upper whorls, when these are crushed and 
dislocated. Weinland, Weichthierf. d. schw. Alb, p. 66. 
A list of different anomalies of land- and freshwater- shells found 
near Esino, in Lombardy, is given by Pini, Moll. terr. di Esino, pp. 
127-129. 
Several varieties and abnormal forms of Limncea stagnalis and L. 
palustris described and figured by H. Strebel, Verb. Ver. Hamb. ii. 
19 pp., 2 pis. 
GEOGRAPHICAL DISTRIBUTION. 
a . Land and Freshwater Mollusca. 
A. R. Wallace gives an outline of the geographical distribution of 
the terrestrial (and freshwater) Mollusca in his “ Geographical Distri- 
bution of Animals,” vol. ii. pp. 512-529 and 534 & 535, and some 
instances of means for their passive dispersal, vol. i. p. 31. Probable 
transportation by fioating cocoa-nuts ; Liardet, P. Z. S. 1876, p. 99. 
P. Strobel discusses the influence of soil on the distribution of ter- 
restrial Mollusca, with special reference to those observed by him in 
