I'.'- Mi:i;i>TI< VARIATION. [PART I. 



structures ,{' smaller si/.- (c"c"). Probably these should be considered 

 as rudiment- ..f extra tarsi : but if tlii.s view is correct, it appears that 

 tu.i extra tarsi ;uv present, arMn^ from different joints. For the loan 

 i.f this -pe.-imen I am indebted to Dr G. KuAATZ, who first cleseribed 

 and (inured it in l>-nt. . ,,t. Xt., 1S77, XXI. pp. - r >7 and 63, tijj;. 27. 



7.; | Chrysomela graminia i I'll ytophagi) : the femur of the right middle leg bears a 



.-up. -111111111 mi -y pair of leg- attached to the posterior and dorsal side of its apex. 

 At this iiuiiit tin-re is an articulation with which the single proximal part of the 

 .-\ti.-t pair of til.i.-i- articulates. This piece, which is common to the two super- 

 nuiiieiaiy tibi;e, i- a -uli globular, amorphous mass from which the two tihi.-e 

 di\.-rge. l.arh of the two tihi.-r- bears a complete tarsus, except that the most 

 jK.-ti-rii.r has only one claw. In colour the two supernumerary tarsi differ from the 

 noMiial, ln-iii;.' liinwn instead of metallic green, but the tibiae are normal in colour. 

 I rom ti of the articulations and the arrangement of the pubescence, it is 



rl.-ar that the surfaces <>t' the l,.gs which are naturally adjacent are constructed as 

 jiu.-itt'rior surfaces, and the foinis of the two are complementary to each other, the 

 himhiiost of the extia It ge li.-ing formed as a left leg, while the foremost is a right 

 leg. A- thi -\ stainl, howe\t-r, the two tibia? are not in the same position relatively to 

 tin- hod\. t,ii tin foremost is placed normally, having its plantar surface turned 

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

 turned n>i-ii-<inlx The relative positions are nearly those marked DP in the Scheme, 

 hut tht 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 

 ainoiphoiis giowth at the base of the extra tibia;. This specimen was kindly lent 

 for description by 1'r Mason. 



~(]'2. Pimelia interstitialis (Tenebrion.) : left posterior femur bears two super- 

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

 a pair, for the tibia nt ait -t to the normal tibia is a riyht tibia, the remoter being a 

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

 \entral Miifac. - 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 

 Neutral sui faces of the extra legs is rather more acute than it would be in the 

 I'ti-itioii I'l'. The. tarsi an- all broken off. Specimen originally described by 

 MOII..I i BT8, ''"/. iinnnii., p. 44, .////. 



7li.'!. 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 i- doubtful. The arrangement is nearly that of Position DP, 

 but as one of the femora is ci msti icted and bent, the relations are rather irregular. 

 Specimen first de-cubed by MOCOUKKYS, Col. <niorm., p. 41,.%. 



(7) Position P. 



"704. Silis ruficollis < Mularndrnii') : right anterior femur bearing 

 a sujKTiminrrai v limb ( Fi.sj. 10.")). The coxa and trochanter normal. 

 Tin' tfimir is of about twice the antero-posterior thickness of a 

 normal frimir ami at its apex presents two articulations in the 

 -ame horizontal plane. Of these the anterior bears a normal 

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

 appears at Hrst 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 tiiimd that this extra tibia is in reality 

 made of the /mxtrrinr surfaces of a /><n'r of tih'ne not separated from 

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

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

 normal tibia is not bilaterally symmetrical about its middle line, 

 the contrary the anterior surface is differentiated from the 



