260 
ARACHNIDA. 
Trombidiides. 
Donnadieu, a. L. Recherches pour servir ^ Phistoire des T^tranyques. 
Lyon & Paris: 1875, 8vo, pp. 1-134, 12 pis. Abstracted by the 
Author, under the title of Recherches sur les T5tranyques, J. Zool. 
iv. pp. 269-263. ^ 
The first stage is tetrapodous or hexapodous, this form having hitherto 
been considered generically distinct, and referred to Tromhidium. It 
exhibits a very evident parthenogenesis, producing by egg a hexapod 
larva, whence the adult form is developed, and from which latter it differs 
in being sexless. 
Tromhidium ? fucicolum^ sp. n., G. S, Brady, P. Z, S. 1875, p. 303 
pi. xli. figs. 1 & 2, North Britain. 
Pachygnathus sculptus^ sp. n., id. 1. c. p. 306, pi. xlii. figs. 1-6, North 
Britain. 
Gamasides. 
M^ignin, — . M^moire sur les Hypopus (Dug^s), Acariens parasites 
encore noram5s Ilomopus^ Koch, et Trichodactylus^ L. Dufour; 
determination de leur position zoologique et de leur r61e physiolo- 
, gique. J. de I’Anat. Phys. x. [1874] pp. 225-254, pis. vii.-x. 
Describes Tyroglyphus mycophagus, M6gn., and its “ Hypope,” A earns 
spiniiarsus^ Herm. ; also T. rostroserratus, M^gn., and its “ Hypopes,’^ 
Hypopus feroniarum, L. Duf., and A?, dugesi^ Clap.; and some undeter- 
mined stages. 
. Sur I’organisation et la classification naturelle des Acariens de la 
famille des Gamasides (P. Gerv.). 0. R. Ixxx. pp. 1335-1338. 
Extract from a memoir (as yet unpublished) on the anatofuy, physio- 
logy, and classification of the group, in which jt will be proved that 
its members form a very natural transition between the Arachnida and 
hexapod insects, possessing anatomical details proper to each class (on 
these characters, cf. M%nin, op. cit. Ixxxi. p. 1135), and that the parasitism 
of Gamasus and Uropoda is peculiar to their earlier stages, the host being 
the unconscious agent for the preservation and dissemination of its 
innocuous parasite. The author states that it is impossible to determine 
a species of Acaridee without knowing its different stages in both sexes. 
Gamasus coleopteratorum is an earlier stage of a species of which G. 
crassipes is the male and G. testudinarius the female. G. tetragonoides is 
the male of G. cellaris. G. marginatus derives its name from a character 
common to all the females of its genus. Uropoda vegetans is an early 
stage of a species of which the adherent apparatus disappears in the adult. 
A table is given of Gamasus, Uropoda, Dermanyssus, and Pteroptes, with 
various sections or sub-genera (unnamed). Argas, Duges, is removed to 
the Ixodides, in spite of its cylindrical palpi. Uropoda scutulata and 
truncata, Pteroptes hortorum, copromorgus, fenilis, mantis, and musci are 
included in the table as (probably) new. 
