* 



5 1 MERISTIC VARIATION. [part i. 



pair of articulated spines, this tibia bears five such spines, of which a pairstaud 

 between the two extra processes. The disposition of these spines could not be made 

 clear without several figures. There are two complete tarsi and both have their ventral 

 surfaces turned downwards. The anterior tarsus is somewhat the smaller. I did 

 not succeed in definitely determining the homologies of the parts in this specimen. 

 It should be specially observed that while the tarsi are only two in number, suggesting 

 that the supernumerary part is single, the spines indicate that there are here at 

 least some elements of further repetition.] Specimen figured bv Kraatz, Deut. ent. 

 '/A., 1889, xxxin, p. 221, fig. 18, and kindly lent by him. 

 7S5. Ranzania bertolonii (Lamellicorn) : in the right posterior foot the last joint of 

 the tarsus is curved outwards and bears six claws instead of two, and three onychia 

 instead of one. The arrangement of the parts is somewhat complex and could not 

 well be made clear without elaborate figures. Speaking generally, the last (fifth) 

 tarsal joint presents at its apex a large articular surface of irregular shape. This 

 surface bears four large claws disposed in the same direction as the normal pair of 

 claws. Of the four claws the two adjacent ones are in solid continuity for a part of 

 their length, being joined together by chitin much as the extra dactylopodites are in 

 Fig. 184, in. It is clearly shewn that the conjoined claws are respectively the fellows 

 of the two free claws, for the two extra onychia stand one upon either side of and 

 opposite to the curvature of the conjoined claws. Terminally the fifth tarsal joint 

 bears also a small pair of somewhat deformed claws with which an enlarged and 

 misshapen onychium corresponds. This specimen was kindly lent to me by M. 

 Henri Gadeau de Kerville and was mentioned by him in Bull. Soc. Ent. France, 

 Ser. 6, vi. 1886, p. clxxx. 



786. Rhizotrogus aestivalis $ (Lamellicorn), bearing supernumer- 

 ary parts of double structure upon the right posterior 5th tarsal 

 joint (Fig. 172). The structure found in this case is very re- 

 markable and is, I believe, in some respects unique. The tarsus 

 is normal as far as the extremity of the terminal joint, and the 

 abnormality consists entirely in repetition of claws and pulvillus. 

 The normal formation is shewn from the ventral surface in 

 Fig. 172, A. There is an anterior claw, a posterior claw and a 

 small pulvillus, placed ventrally to the claws, bearing two hairs. 

 Fig. 172, B, shews the abnormal foot from the ventral side. Each 

 claw gives off from its base a ventrally-directed supernumerary 

 claw, and each supernumerary claw is bifid at its point. Ex- 

 amined from below each of these extra claws is seen to bear 

 two grooves separated by a ridge, and is therefore morphologically 

 a double structure. The next structure of importance is the 

 pulvillus. The normal pulvillus (pul) is in place and of the usual 

 form, but dorsally to it there is a supernumerary pulvillus (pvP) 

 of cylindrical form and rather longer than the normal pulvillus. 

 At its apex this extra pulvillus bears a median bifid hair with 

 another hair on each side of it ; these hairs thus prove that the 

 extra pulvillus is morphologically double. 



In this foot, therefore, a supernumerary pair of claws and a 

 supernumerary double pulvillus are intercalated between the 

 normal claws and the normal pulvillus. Hence though the repet- 

 ition affects both claws and pulvilli, and the structures found 

 are sufficient for an incomplete pair of extra feet, yet the extra 

 parts arc disposed in the system of symmetry of the normal foot, 

 forming, all taken together, one foot only. Specimen very kindly 

 lent by Dr G. Kraatz. 



