CHAP. XX.] 



EXTRA LEGS : POSITION V. 



483 



with the Position V and taking the other radii in order, going 

 round against the hands of a watch. 



Cases of Extra Legs in Secondary Symmetry. 



(1) Position V. 



*736. Carabus scheidleri % : pair of extra legs having a common 

 femoral^ portion arising from the trochanter of the right fore leg 

 (Fig. 155). This case is of diagrammatic simplicity. The troch- 



Fig. 155. Carabus scheidleri, No. 736. The normal right fore leg, R, bearing 

 an extra pair of legs, SL and SR', arising from the ventral surface of the coxa, C. 

 Seen from in front. (The property of Dr Kraatz.) 



anter bears a normal leg (R) articulating as usual. Immediately 

 ventral to this articulation there is a second articulation upon a 

 small elevation. This bears a double femur made up of jDarts 

 of a pair of femora compounded by their dorsal borders. The 

 double femur has thus two structurally ventral surfaces opposite 

 to each other. 



The apex presents two articular surfaces in the same plane 

 as that of the normal leg, each bearing a tibia, both tibiae flexing 

 in the same vertical plane. 



Since the double femur of the extra legs stands vertically 

 downwards at right angles to the normal femur, it will be seen 

 that both the extra tibiae flex upwards, but one of them is a 

 left leg (SL), bending to meet the normal leg, while the other 

 is a right (SR') } bending towards the ventral surface of the body. 

 The tibia of the left extra leg is a little shorter than that uf 

 the normal, and the tibia of the right extra leg is a little longer 

 than it. All three tarsi are thinner than a normal tarsus; and 

 the claws are a good deal reduced in the case both of the normal 

 and the right extra leg, while in the left extra leg they are absent 

 altogether. This is an example of a pair of extra legs arising 



31—2 



