On Melohnthid and Rutelid Cohoptera. 303 



In view of the great complexity of the subject and the 

 small amount of information as yet available on several im- 

 portant points, it will easily be understood that the above 

 arrangement only professes to be tentative *. It is given 

 here not alone for its own interest, but because it shows 

 very clearly a phenomenon often to be met with in the 

 attempt to deal with problems of this kind. The group of 

 genera on the right-hand branch have broad, usually well- 

 regioned bodies f, and legs which are knobbed and ridged 

 (except the walking-legs of Dromia). Those on the left- 

 hand branch have simple legs and narrow bodies, almost 

 without trace of regions. Now, the names followed by a star 

 are tliose of genera wdiich have lost the epipodites of their 

 chelipeds, and it is easy to see that a division made on this 

 feature would cross that made on the shape of the body and 

 legs. Again, the genera after whose names a dagger stands 

 are those in which the sternal grooves end together, so that 

 by these grooves a third separation could be made. And, 

 to take one more criterion, a thorn appears on the outer side 

 o£ the last joint of the fifth leg in genera which, on other 

 grounds, are separated as widely us Drotnidiopsis and Crypto- 

 diomu psis. Indeed, the whole tree is a good example of tliat 

 kaleidoscopic shuffling of characters which so often meets the 

 student of zoological genealogy, and whose interest lies in the 

 suggestion that it makes of a tendency in the organization of 

 the animals in which it is found to fall into certain types of 

 structure somewhat reminiscent of the discontinuous variation 

 ot the Neo-^lendelians. 



XLI. — On the Affinities and Nomenclature of certain Genera 

 of Melohnthid and Rutelid Coleoplera. By GILBERT J. 

 Arrow. 



]n Gemminger and Harold's Catalogue of the Coleoptera 

 the genus Stethaspis (in the Melolonthids) is represented by 

 the single species suturalis, Fabr., of which Micromjv cUoro- 

 jjhyllus, Boisd., and Paianonca prasina, Cast., figure as 

 synonyms. Lacordaire expressed himself very doubtful of 

 the correctness of the latter identification, and in 1873 Para- 

 nonca was referred by Lansberge to its right position with the 



* This is especially the case with Lasiodromia, Cryptodromiopsis, and 

 Jhomidea, whose position is extremely doubtful. 



t With some exceptions it may be said that species belonging to 

 geuoia on the right hall" of the diagram are broad, those ou the left long. 



