Page:VCH Warwickshire 1.djvu/212

 A HISTORY OF WARWICKSHIRE gills attached to the trunk-legs several appendages of the pleon supply the respiratory organs. Amphipods are usually, though not always, laterally compressed. This puts them at a disadvantage for walking in the open air. But isopods, being almost always dorso-ventrally depressed or flattened downwards, have a more stedfast equilibrium, such as is well exemplified in A. aquaticus. The brown colour marbled with white, the long antenna? in front, and the slender two-branched uropods or tail-feet prominently projecting from the consolidated pleon behind, make this exceedingly common species easy to recognize. It is fully and beautifully illustrated in an early work 1 by the distinguished Norwegian carcinologist, Professor G. O. Sars, and more concisely in his recent description of the Isopoda of Norway. 2 Of the Isopoda terrestria, or woodlice proper, if so unscientific a term can be called proper, Warwickshire might be thought to be wholly destitute, to judge by the silence of its zoological records. It is however quite certain that in this county as in others Oniscus ase//us, Porcellio scatter, Philoscia muscorum, Armadillidium vu/gare and various other species are to be found, in gardens and woods, in dry ditches by the roadside, and almost anywhere under loose flat stones, amidst decaying leaves and rubbish, or wherever their necessary food and shelter and a modicum of moisture can be obtained. In the case of A. vu/gare and a few other species that stable equilibrium with which nature has provided an isopod can be sacrificed at will, the creature being able to ' conglobate ' its body and roll out of reach of its enemies sometimes in a manner very un- expected. Of the Entomostraca Mr. Bolton writes as follows : 9 'The members of this sub-class are also to be found everywhere, but it is desirable to call special attention to the discovery for the first time in Great Britain of the wonderfully transparent Leptodora hyalina^ at a visit of the Birmingham Natural History and Microscopical Society in 1879 to the Olton reservoir near Solihull. It has since been found in many localities, and is very abundant in the summer and autumn in the Warwick Canal and several reservoirs. Hyalodaphnia kahlbergensis is very generally found with it. Argulus coregoni is found in the Birmingham and Warwick Canal. It had only been discovered in Great Britain previously in the tanks of the Royal Aquarium at Westminster, which of course are not used for British fish exclusively. The fairy shrimp, Chirocephalus diaphanus, is found in only one locality in the district, near Knowle. A few specimens of the very rare Lynceus acanthocercoides were found near Bewdley, and amongst other local finds may be mentioned Moina rectirostris, Macrotbrix roseus and Ilyocryptus sordidus? To make clear the relations one to another of these and several other Warwickshire species it will be expedient to give in brief an outline of the classification now generally adopted for the Entomostraca. 1 Hittoire Naturelle des Cruttacet feau douce de Notvege, p. 93, ph. 8-10 (1867). 3 Handbook of Birmingham, p. 306. 174
 * Crustacea of Norway, ii. 97, pi. 39 (1899).