ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
181 
Eye of Phalangiidae.* * * § — Mr. F. Purcell finds from his investigation 
of Leiobanum hemisphsericum tliat tlio eyes of Phalangiidae are compound 
eyes. The retinal cells are arranged in groups. Each of these retinulae 
consists of four cells, one central and three peripheral. The strongly 
refractive rods of the four cells lie at the distal end and fuse in one 
triradiate rhabdomo. The original eye-fold, the formation of two eye- 
pockets, and the development of these pockets into eyes, are briefly 
described. A thickening of external epithelium over the pockets forms 
the vitreous body ; the lens arises at the first eedysis as a cuticular 
product of the same epithelium ; the outer wall of the pockets becomes 
the retina; the fate of the inner wall was not precisely observed. The 
eyes of Phalangiidae are thus inverse eyes, homologous with the anterior 
middle eyes of spiders and with the middle eyes of scorpions. 
Nerve-Ganglion in Legs of Phalangium opilio.j — M. Gaubert 
points out that while the parts of limbs of Crabs and Spiders detached 
by autotomy remain motionless and in a state of contraction those of 
Phalangium opilio exhibit for some minutes convulsive movements ; the 
movements are ascribed to a ganglion which is to be found on the pedal 
nerve at a point in the third joint of the leg where the trunk gives off a 
nerve-branch ; the movements are not, therefore, as the author first 
supposed, due to direct stimulation of the nerve. When the leg is quite 
uninjured the ganglion in question is probably under the influence of 
the superior centres which correspond to the thoracic ganglia. 
Types of Larvae among Freshwater Mites.J — Prof. P. Kramer 
describes three chief forms : — (1) the larva of Hydrachna C. L. Koch ; 
(2) the larva of Nessea C. L. Koch (also Piona , Atax , Hygrobates , &c.) ; 
(3a) the larva of Diplodontus filipes Dug. (also Hydrodroma) ; (3b) the 
larva of Eylais extendens. There is much reason to regard Diplodontus , 
Hydrodroma , Eylais, and perhaps also Limnochares and Bradybates, as 
descendants of Trombididae. The author thinks that there must have 
been several migrations of “ Prostigmata ” from the land into the fresh 
water ; the latest migration of Trombididae is not ancient enough to have 
become associated with deep modifications of the larvae, thus we have 
those of Diplodontus , Hydrodroma , Eylais , Limnochares, adapted for 
terrestrial rather than for aquatic life ; a much more ancient migration 
led to such types as Hydrachna and Nessea whose larvae are genuinely 
aquatic. Kramer upholds his order of Prostigmata, which includes 
Hydrachnidae, Eylaidae, Hygrobatidae, and Trombididae. 
Chernes on a Tipulid.§ — Dr. F. von Wagner describes the case of a 
Tipulid (Ctenophora pectinicornis) on the legs of which Herr H. Friese 
found four blind Pseudoscorpionidae of the genus Chernes ( Ch . Hahnii). 
He thinks it likely that the Chernes simply utilizes the fly as a means 
of transport. 
Peculiar Parasite of the Goura.||— Dr. L. Karpelles describes a 
peculiar cutaneous and subcutaneous parasite which seems to have 
* Zool. Anzeig., xv. (1892) pp. 461-5 (3 figs.). 
f Comptes Rendus, cxv. (1892) pp. 960 and 1. 
X Arch. f. Naturg., lix. (1893) pp. 1-24 (1 pi.). 
§ Zool. Anzeig., xv. (1892) pp. 434-6 (2 figs.). 
|| Verhandl. Zool.-Bot. Gesell. Wien, xlii. (1892) pp. 46-7. 
