494 MERISTIC VARIATION. [part I. 



indicated in the Scheme for the position DAA. This specimen was described by M. 

 A. Fauvel (Rev. (VKtit., 188 ( J, p. 331) and was kindly lent by him for further 

 examination. 

 755. Chrysomela banksii iPhytophagi) : right hind tibia bearing an extra pair of 

 tai-si. The border of the tibia which corresponds in position to the ventral or flexor 

 border of the normal tibia is covered with the hairs which characterize it in the 

 normal limb; but the ojjposite border of this abnormal tibia is similarly covered 

 with hairs, shewing that the anterior parts of at least two tibiae are included in it. 

 A rigid process projects from the wide apex of the tibia. Upon the inner side of 

 this process is the articulation for the tarsus, which from its direction and position 

 appears to be the normal tarsus of the limb. Outside the process articulates a 

 slightly smaller tarsus, which from its form and from the plane in which it moves 

 is a left tarsus, flexing away from the normal one. At a point slightly external to 

 this is the third tarsus, which is again a right tarsus and moves in a plane comple- 

 mentary to the middle one. The two are therefore a pair. The position of origin 

 lb anterior and dorsal, being nearly that marked DA, but the relative positions of 

 the extra tarsi are approximately DDA. As to the nature of the tibial process I can 

 make no conjecture. (Fig. 161.) 



Fig. 161. Chrysomela banksii, No. 755. View of right hind tibia from posterior 

 surface. A normal right hind tibia is shewn for comparison. (From Pruc. Zuol. 

 Soc, specimen the property of Dr D. Sharp.) 



This specimen is the property of Dr Sharp, who was good enough to lend it to 

 me. It was briefly described and figured by me P. Z. S. , 1890, p. 583, but 1 was not 

 at that time aware of the complementary relation existing in these cases and failed 

 to notice the somewhat inconspicuous differences which are evidence of it in this 

 case. 

 756. Hylotrupes bajulus (Longic): right middle tibia bears a suj^ernumerary 

 pair of limbs having proximal parts in common. From the antero-dorsal surface of 

 the base of the normal tibia, there arises a slender tibial piece which is not so long 

 as the normal tibia and bears no spurs. At the apex of this supernumerary tibia, 

 which is doubtless a double structure, articulate a pair of tarsi having their 

 first and second joints compounded together. After the second joint the tw r o tarsi 

 separate from each other and each bears a pair of claws. The relative position of 

 the two tarsi when they separate from each other is almost exactly that marked DA. 

 It should be mentioned that the supernumerary parts central to the 3rd tarsal joints 

 are not fully formed, being deficient in thickness, and the transverse separation 

 between the 1st and 2nd tarsal joints is incomplete. Specimen first described by 

 Mocquerys, Col. anorm., 1880, p. 53, fig. I am indebted to Dr L. vox Heydex 

 for an opportunity of examining it. 



(5) Position D. 



*757. Aphodius contaminatus <£ (Lamellicorn.) : left middle tibia 

 bearing two supernumerary tarsi which stand very nearly in the 

 position DDP, being rather nearer to D. The relative positions 

 are shewn in Fig. 162. The articular surface at the apex of the 

 tibia is extended along an elongated process which projects on 

 the dorsal side of the tibia. Upon this extension of the apex 

 articulate two extra tarsi. They stand with their ventral or 



