ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
301 
its inclusions, are formed from the cells of the Jibrilloplast-zone. Each 
epithelial cell makes numerous fibrils, as to the cuticular nature of which 
there can be no doubt. But the oikoplast region of the integument also 
includes membranoplast- cells, which form membranes in part composed 
of a trelliswork of threads and bands. The membrane has its surface 
at right angles to the secreting cells; its formation is comparable to 
that of periostracum and ostracum in Molluscs, while that of the fibrillar 
mass corresponds to that of the liypostracum. But both are truly 
cuticular ; and the casting of the “ house,” which occurs in two stages, 
first affecting the fibrillar part, and then the membranous part, is com- 
parable to ecdysis. 
The author also discusses some questions of distribution. 
INVERTEBRATA. 
Fauna of Wells.* — Herr. A. Jaworowski has made a study of the 
fauna of the wells of Krakau and Lemberg, and has found some 
novelties: — A monostomatous Khizopod, Quadrula acolis ; two amphi- 
stomatous Bhizopods, Diplophrys elongata and D. Graberi ; Cothurnia 
puteana and C. cyathus among the Infusorians ; Mesostoma Vejdovskyi 
among Turbellarians ; and a Gammarid Niphargus leopoliensis. He 
gives a detailed description of the last, and a diagnostic key to the other 
species of the genus. 
Distribution of Terrestrial Invertebrates.! — Herr 0. Stoll con- 
tinues his studies on this subject, discussing as two particular cases the 
distribution of the species of the Gamasid Megisthanus (including 
M. afer sp. n.) and the Pulmonate Clausilia. 
The members of the genus Clausilia must be included among the 
persistent types which have lasted long and travelled far without under- 
going, so far as their shells indicate, any essential modifications in their 
generic characters. They are represented in widely separated islands 
by over 1000 species, and yet without divergence from the generic 
characters. Similarly, in Megisthanus , with few but widely separated 
species, there is an equally marked absence of divergence. 
Mollusca. 
a. Cephalopoda. 
Histology of Optic Lobes in Cephalopoda, f — Herr M. v. Lenhossek 
has investigated this subject with a view to determining the relation of 
the retina of Ceplialopods to that of Vertebrates. The Cephalopod 
chosen was Eledone, of which immature specimens were taken. The 
author describes in detail the anatomical relations of the optic lobes, and 
their histological structure as seen in sections. The substance of the 
lobes shows a division into cortical and medullary zones. The cortical 
zone resembles strongly the retina of a Vertebrate, and consists of an 
outer and an inner granular layer, separated by a plexiform layer. The 
* Arch. f. Naturgesch., lxi. (1895) pp. 319-15 (1 pi.). 
t Vierteljalirschr. Nat. Gesell. Zurich, xl. (1895) pp. 288-316 (2 pis.). 
X Arch. f. Mikr. Anat., xlvii. (1896) pp. 45-120 (3 pis. and 3 figs.). 
1896 Y 
