498 MEBTSTIC VARIATION. [part i. 



structures of smaller size (c"c"). Probably these should be considered 

 as rudiments of extra tarsi ; but if this view is correct, it appears that 

 two extra tarsi are present, arising from different joints. For the loan 

 of this specimen I am indebted to Dr G. Kraatz, who first described 

 and figured it in Deut. ent. Z&, 1877, XXI. pp. 57 and 63, tig. 27. 



•rgj Chrysomela graminis (Phy tophagi) : the femur of the right middle leg bears a 



supernumerary pair of legs attached to the posterior and dorsal side of its apex. 

 At this point' there is an articulation with which the single proximal part of the 

 extra pair of tilme articulates. This- piece, which is common to the two super- 

 numerary tibia?, is a sub-globular, amorphous mass from which the two tibia? 

 diverge. " Each of the two tibia? bears a complete tarsus, except that the most 

 posterior has only one claw. In colour the two supernumerary tarsi differ from the 

 normal, being brown instead of metallic green, but the tibia? are normal in colour. 

 From the shape of the articulations and the arrangement of the pubescence, it is 

 clear that the surfaces of the legs which are naturally adjacent are constructed as 

 posterior surfaces, and the forms of the two are complementary to each other, the 

 hindmost of the extra legs being formed as a left leg, while the foremost is a right 

 leg. As the}' stand, however, the two tibia? are not in the same position relatively to 

 the body, for the foremost is placed normally, having its plantar surface turned 

 downwards, but the hindmost is rotated so that its plantar surface is partially 

 turned forwards. The relative positions are nearly those marked DP in the Scheme, 

 but the most posterior tarsus is more rotated than it should be according to that 

 diagram. This condition may be to some degree connected with the presence of the 

 amorphous growth at the base of the extra tibia?. This specimen was kindly lent 

 for description by Dr Mason. 



762. Fimelia interstitialis (Tenebrion.) : left posterior femur bears two super- 

 numerary tibia? arising from the postero-dorsal surface of its apex. These two are 

 a pair, for the tibia nearest to the normal tibia is a right tibia, the remoter being a 

 left. The adjacent surfaces are chiefly anterior surfaces in structure, but the 

 ventral surfaces are inclined to each other at an obtuse angle. The position of the 

 extra legs is almost that marked DP in the Scheme, but the inclination of the 

 ventral surfaces of the extra legs is rather more acute than it would be in the 

 Position DP. The tarsi are all broken off. Specimen originally described by 

 Mocqvekys, Col. anorm., p. 44, fig. 



7Q3 Acinopus lepelletieri (Carab.): two extra legs arising from posterior surface 



of base of femur of /. middle leg. From position it seems that the most anterior is 

 the normal, but this is doubtful. The arrangement is nearly that of Position DP, 

 but as one of the femora is constricted and bent, the relations are rather irregular. 

 Specimen first described by Mocquerys, Col. anorm., p. 41, Jig. 



(7) Position P. 



*764. Silis ruficollis^ (Malacoderm) : right anterior femur bearing 

 a supernumerary limb (Fig. 165). The coxa and trochanter normal. 

 The femur is of about twice the antero-posterior thickness of a 

 normal femur and at its apex presents two articulations in the 

 same horizontal plane. Of these the anterior bears a normal 

 tibia and tarsus, but the posterior bears an extra tibia which 

 appears at first sight to be a single structure. This tibia is more 

 slender than the normal one and is provided with four tarsal 

 joints, the terminal one being withered and without claws. Upon 

 closer examination it is found that this extra tibia is in reality 

 made of the posterior surf aces of a paii; of tibice not separated from 

 each other. In this case the morphological duplicity of the extra 

 tibia is capable of proof. For, as shewn in Fig. 165, II, the 

 normal tibia is not bilaterally symmetrical about its middle line. 

 On the contrary the anterior surface is differentiated from the 



