Page:VCH Derbyshire 1.djvu/159

 CRUSTACEANS tor the report of this interesting addition to our fauna, I hazarded the prophecy that we should find the species also in England. It so hap- pened that early in the following June I had occasion to visit Matlock Bridge with my wife. A couple of days after our arrival we set ourselves to seek out such localities as were likely to harbour terrestrial Isopoda. We had scarcely been engaged five minutes in the first favourable spot when Mrs. T. R. R. Stebbing exclaimed that she seemed to have found something new. This was really the case, and though, as subsequent researches showed, the specimens were not very numerous, they justified my venturesome prediction by proving to be the veritable Armadillidium pulchellum of Brandt, as described by Budde-Lund in 1885. It should however be mentioned that the latter author ascribes the honour of having first named this pretty little species not to Brandt but to Zencker. It is further worth noting that, though A. vulgare is usually black and uniform in colouring, there are sometimes found specimens brightly mottled with three or even four rows of yellow spots along the back. It is therefore desirable to reproduce in part Budde-Lund's description of the species A. pulchellum^ which is not only new to England but as yet peculiar therein to this county. The length is a fifth of an inch, with a breadth of about half the length. It is thus much smaller than the other English members of the same genus. In regard to shape and texture it is oblong oval, very convex, smooth, shining, minutely but not very densely punctate. The outer antenna? are equal to three- sevenths of the length of the body, and the flagellum has its first joint one-third as long as the second. This last is an important character, because in A. vulgare there is much less difference and in the other two British species little or none in the length of these two joints. In the first segment following the head the lateral margin just in front of its hinder angle is obliquely sub-truncate. The terminal segment of the pleon is broader than long, sub-semicircular. The colour is brown with the margins and four rows of spots yellow or beautifully red. The seventh segment of the trunk is almost entirely black. 1 In the figure which accompanies Dr. Scharff's paper this last character does not appear, nor is it mentioned in his notes on the colouring. In the Derbyshire specimens the seventh segment has the light spots sometimes pretty strongly developed, but in every case flanked on either side by a dark patch. Thereby this segment is in rather a marked manner dis- tinguished from the preceding segments which have the lateral parts of the dorsal surface light-coloured. Of the Amphipoda little is yet known from Derbyshire. These sessile-eyed Malacostraca are commonly regarded as a companion group to the Isopoda. They have the body similarly divided, the middle part being composed of seven distinct leg-bearing segments. But whereas in the Isopoda the appendages of the abdomen have some parts modi- fied for the respiratory function, in the Amphipoda this purpose is served by branchial sacs attached to several of the trunk-legs. In this respect 1 Budde-Lund, Isopoda Terrestria (1885), p. 70. 107