312 GAMMARIDJK. 



The hands of the first two pairs of legs are nearly of 

 the same size and form. The legs are of different 

 lengths, the last pair being the longest. The ante- and 

 penultimate pairs of caudal appendages are short their 

 branches being about the length of the peduncle and 

 equal ; whilst those of the last pair are unequal, one 

 being very minute and the other extremely long, 

 especially in the male;* it is also double-jointed. The 

 central tail-piece is single, but cleft down the centre. 



The earliest specimen of these subterranean Amphi- 

 poda was that recorded by Dr. Leach as having been 

 found in a well attached to St. Bartholomew's Hospital. 

 But this was looked upon rather in the light of a strange 

 occurrence than the establishment of a fact in the habits 

 of these creatures. 



Between the years 1835 and 1842, Koch, in the con- 

 tinuation of Panzer's great work on the Insects of Ger- 

 many, published descriptions and figures of two species 

 which he procured from the draw-wells of Ratisbonne 

 and Zweibriicken, under the single name of Gammarus 

 puteanus. In 1851 Schioclte obtained other specimens 

 from the Caves of Carniola ; and to him is due the 

 credit of establishing this interesting genus among the 

 Amphipod Crustacea. In the year 1852 Prof. West- 

 wood was so fortunate as to obtain from a pump with 

 a substratum of clay, near Maidenhead, a quantity of 

 these animals, since which they have been found in 

 Hampshire, Wiltshire, Kent, Surrey, Dorsetshire, De- 

 vonshire, Worcestershire, and very recently in Dublin. 



In all these instances the British examples have been 



* It is upon the authority of Schioclte that we assert that the males in this 

 genus differ from the females in the length of the last pair of caudal 

 appendages, since we have not procured a specimen which we could determine 

 upon other evidence to be female. 



