CRUSTACEANS unready and inexpert. Its glossiness, its nimble movements, its red- brown colour, and its angular outstanding spiny little second antennae make it easy of recognition. Haplophthalmus danicus, Budde-Lund, was not known in England until discovered by Dr. Norman, who says, ' I have found this pretty little species in my garden here (the Red House, Berkhamsted, Herts). It occurs in company with Trichoniscus roseus in a cool greenhouse. The genus is allied to T'richoniscus. The species may be recognized by its simple eyes and the longitudinal series of tubercles which pass down the body. Other specimens in my collection are from Denmark (Copenhagen Mus.). It has also been found in Norway, Holland, and France. A near ally, H. mengii, Zaddach, which is known to have a wider distri- bution, may be found in Great Britain. It is distinguished from its ally by having six longitudinal finely crenulated ribs passing down the body, instead of the rows of tubercles, and by the peculiarity of having two very prominent ribs on the back of the third segment of the pleon.' 1 This quotation may serve to stimulate research for these minute forms, in which, as the generic name implies, the eyes are simple. In Trichoniscus the eyes have each three visual elements. Haplophthalmus danicus is greyish white in colour, and not quite a sixth of an inch long. The companion species is scarce an eighth of an inch long, but Professor Sars says that 'it moves very slowly, and, in spite of its small size, is easily detected by the pure white colour of the body.' Yet, as the young ones of some of the larger woodlice are also slow-moving, small and white, there is opportunity for untrained eyes to be deceived. The six following species are all included in the family Oniscidae : Oniscus aseHus, Linn., is found not only here, but everywhere, if by everywhere we are contented to understand Europe and North America, with the Azores, Iceland, and Greenland. As it attains a length of two- thirds of an inch, and is one of the broadest of our woodlice, its familiar form can be discerned by most persons without the aid of microscope or even spectacles. Philoscia muscorum (Scopoli), though not nearly so large as the preceding, is of respectable size and very common, the inseparable com- panion of rural life. Platyarthrus hoffmannseggii, Brandt, is humble in size, though so ample in name. Its legs are short and thick, and the second antennae have the joints of the peduncle flattened, whence Brandt gave it a generic name meaning broad of limb. But it has no eyes, so that another author, Schobl, later on, in ignorance of Brandt, named the genus Typhlo- niscus, meaning the blind woodlouse ; while in between these two authors Koch called the species Itea crassicornis, in allusion to the thickness of its antennae. Notwithstanding its extensive distribution, the only chance of finding it is by peeping into ants' nests, and then when the disturbed ants are scurrying about, as if the world depended on the security of their offspring, it is an almost pathetic sight to see the little white, sight- 1 Annals and Magazine of Natural History, ser. 7, vol. iii. p. 73 (1899). 185
