20 Moll. 
MOLLU8CA. 
Fresh observations on the parasitism of the liver-fluke, Distoma hepa- 
ticum , in Limncea trunCatula, the Cercarice leaving the snails, and encyst- 
ing themselves on a blade of grass, by A. P. Thomas, Q. J. Micr. Sci.. 
January, 1883 ; abstract in J. of Conch, iv. pp. 10-12. 
Leidy has observed on the gills of the North American Anodonta jluvia- 
tilis, a mite which he declares to be identical with that found on European 
Anodontce, viz., A tax hypsilophorua (Bonz.) ; P. Ac. Philad. 1883, pp. 44 
& 45; abstract in Ann. N. H. (5) xi. pp. 391 & 392, Science, i. p. 150, 
and Nachr. mal. Ges. 1883, p. 116. 
11 . Abnormities. 
An instance of closure of the external genital opening in Helix pomatiu; 
0. Maugenot, Bull. Soc. Z. viii. pp. 130-133. 
The green colour in oysters is due to staining of the blood-cells, and is 
sometimes most intensive in the hepatic follicles ; it may be caused by 
the food ; the author very much doubts whether it may be chlorophyll, 
and rejects altogether the idea that it is produced by Diatomacea : J. A. 
Ryder, Am. Nat. xvii. pp. 86-88 ; abstract in J. R. Micr. Soc. (2) iii. 
p. 194. Oysters with green-coloured gills are not hurtful to man ; id. 
Bull. U. S. Fish. Comm. iii. p. 294. 
White varieties of Limncea palustris; Morris, J. of Conch, iii. p. 392. Of 
Planorbis niiidus and spirorbis, Limncea per egr a ; Nelson, op. cit. iv. p. 19. 
Of Helix lapicida] Hele, l. c. p. 27. Of Zonites fulvus, Helix virgata and 
cantiana , Succinea elegans , and Planorbis lineatus , pp. 28-37, Pupa mar- 
ginata, p. 44, Helix hortensis , p. 53, Bulimics obscurus , pp. 83 & 84, Physa 
fontinalis, p. 84, Helix rotundata , p. 125 ; Taylor, l. c., all British. (See 
also Roebuck, l. c. p. 117.) 
Sinistral specimens of Helix aspersa , hortensis , and virgata, Planorbis 
complanatus , and Valvata piscinalis, all British, Taylor, J. of Couch, iv. 
pp. 35-37 & 100; of Helix ericetorum (Mull.), Weinland, JH. Ver. 
Wiirtt. 1883, p. 121 ; H. quimperiana (F6r.), Daniel, J. de Conch, xxxi. 
p. 380 ; H. lychnuchus (Mull.), Maz6, /. c. p. 12, pi. i. fig. 5. 
Scalarid of Helix nemoralis , British, Taylor, J. de Conch, iv. p. 53 ; of 
H. aspersa , id. 1. c. p. 101 ; of Planorbis complanatus s [niarginatus'],\di. 1. c. 
p. 128 ; P. rotundatus in Belgium, J. de Guerne, P.-v. Soc. mal. Belg. xii. 
p. vi. 
Bulimoid deformation of Helix pomatia, caused by a fracture on the 
beginning of the third whorl ; Crosse, J. de Conch, xxxi. p. 401, pi. x. 
fig. 7. 
Malformed specimens of Limncea peregra in large proportion to the 
whole number, most of them having added a quarter or one half a whorl 
after forming an expanded lip ; W. Nelson, J. of Conch, iv. p. 80. 
F. C. Noll states that the shells of Limncea truncatula , Bithynia tenta- 
culata , and Planorbis nitidus become eroded and of carious appearance 
even in young animals, if kept alive in confinement in an aquarium, and 
he found that the eroded spots were occupied by numerous specimens 
of Micrococcus , which he therefore thinks the cause of the alteration ; 
Zool. Gart. xxiii. [1883] pp. 157-159. 
