CHAP. XX.] 



EXTRA LEGS : POSITION A. 



487 



45. 



'46 





but as has been mentioned, by the curvature of the double femur its 

 base is somewhat dorsal to the single limb. This specimen was very 

 kindly lent to me by Dr L. Von Heyden and was first described and 

 figured by him in Deut. ent. Zt., 1881, xxv. p. 110, fig. 25. 



(3) Position A. 



Eurycephalus maxillosus (Longic): right anterior femur 

 divides at base into two parts, of which the posterior bears a 

 normal leg. The other part of the femur is bilaterally sym- 

 metrical, being made up of the anterior surfaces of two femora, 

 for both sides present the same convexity (Fig. 157), neither 

 being flattened as the posterior surface of a normal first femur 

 is. With the apex of this joint ar- 

 ticulates a bilaterally symmetrical 

 tibia of extra width, bearing a 1st 

 and 2nd tarsal joint, each of nearly 

 double width. 



The 2nd tarsal joint bears two 

 3rd tarsal joints, which are both 

 much wider than the normal 3rd 

 joint of the tarsus. (This is exag- 

 gerated in the diagram.) One of 

 these in 1891 bore a perfect ter- 

 minal joint with a pair of claws ; but 

 the terminal joint and claws of the 

 other side were gone, though Moc- 

 querys' figure shews that they were 

 originally present. Mocquerys' state- 

 ment that "la cuisse anterieure du 

 cote droit se bifurque des soil origine 

 en deux br'anches ay ant chacune le 

 volume dune cuisse normale" is mis- 

 leading, as suggesting that the two 

 femora are similar, while upon closer 

 examination they are seen to be 

 dissimilar. Here a pair of extra legs 

 arising from the anterior surface of 

 the normal limb, are compounded 

 together as in the position marked 

 A in the Scheme. Specimen origin- 

 ally described by Mocquerys, Col. 

 anorm., 1880, p. 54, fig. 



Eros minutus (Malacoderm) : right anterior tibia slightly 

 divided at apex, forming two apices (Fig. 158). The posterior 

 apex bears a normal tarsus. The anterior apex bears a double 

 tarsus having the first three joints simple (3rd being enlarged). 

 The 4th joint is of nearly double width and bears peripherally 

 two claw-joints each with a pair of claws. From the structure 



Fig. 157. Eiirycejihahis maxil- 

 losus. Eight anterior leg bearing 

 an extra pair arising from the 

 femur. E, the normal right. SL, 

 supernumerary left. SR, super- 

 numerary right, p, posterior sur- 

 face, a, anterior surface of normal 

 femur, a', a", the two structurally 

 anterior surfaces of the extra legs. 

 (In Eouen Mus.) 



