chap, xx.] EXTRA LEGS: POSITION VPP. 501 



VPP in the Scheme, the compounded parts of the extra ap- 

 pendages, viz., the double tibia and the double first tarsal joint 

 have two complete ventral surfaces inclined to each other at an 

 obtuse angle, while there are only two halves of dorsal surfaces. 



Fig. 166. Ceroglossus valdivia, No. 768. Left 

 anterior tibia with extra parts seen from the 

 ventral surface. L, the normal left tarsus. R' and 

 L', the extra tarsi, compounded in their proximal 

 joint. A, anterior. P, posterior. 



Note that the anterior spur of the normal is 

 curved and that the double spur representing the two 

 anterior spurs of the extra tibial apices has thus a 

 bifid point. (Specimen the property of Mr E. W. 

 Janson.) 



Similarly there are two structurally posterior surfaces, but no 

 structurally anterior surfaces, for these are adjacent and un- 

 developed. This specimen was kindly lent by Mr E. W. Janson. 



Silpha nigrita (Heteromera): from right middle femur arises a 

 pair of legs which are completely united as far as the apex of the last 

 tarsal joint. The point of origin of the supernumerary limbs is on the 

 anterior and ventral border of the femur. The form of the extra limbs 

 is shewn in Fig. 167. The surfaces V and V are structurally ventral 

 surfaces. They are turned chiefly forwards, but are inclined to each 

 other at an acute angle. The surfaces, therefore, which are adjacent 

 in this pair of legs, and which are consequently obliterated, are chiefly 

 the morphologically anterior surfaces and to some extent the dorsal 

 surfaces. The plantar or ventral surfaces of the last tarsal joints are 

 inclined to each other rather more obtusely than those of the tibia?, so 

 that the curvatures of the two pairs of claws are very nearly turned 

 forwards as well as away from each other. This is not fully brought 

 out in the figure. The position of origin is about VP, but the claws are 

 in Position VPP. Specimen first described and figured by Mocquerys, 

 Col. anorm., p. 43, Jiff. 



