the Coleopterous Genus Hesodon. 505 



{li[Ti.'i\nt groups seems to indicate tlie genus us lepiosenting 

 the ancestral type from which l>oth have been derived. 

 Aherraiit as it is, it is not remotely related to Dyscinetus and 

 the rest of the Cyclocephalini, in which, however, the more 

 recent character of the contraction (instead of elongation) of 

 the front tarsus of the male prevails, elongation being an 

 ancient condition found in many groups of Lamellicornia, 



The Cyclocephalini are a large and flourishing group, 

 almost entirely contined to America. Ruteloryctes trislis, 

 Arrow, is a solitary representative in Africa, and it seems 

 that liexodon is another example of the survival in Mada- 

 gascar of an ancient type formerly widespread, but now 

 almost extinct in the Old World. There is great dis- 

 similarity in aspect, as there must also be in habits, between 

 IJe.codon and the flower-liaiiuting Cyclocephalini of the New 

 World, and it seems that, as with Htjpocephulus and many 

 other " living fossils," survival from the remote past has 

 been due to the acquisition of peculiar sluggish and lurking 

 habits. 



In the ' Catalogue of Madagascar Coleoptera ' by M. 

 AUuaud published in 1900, four species of Hexodoii are 

 enumerated; but of these II. hopei, Koll., as I have found 

 by examination of Hope's original specimen at Oxford, is 

 identical with H. imicolor, Oliv. Another name, H. rotunda- 

 turn, occurs upon the plates published long before in con- 

 nection with the same work, and the examination in the 

 Paris Museum of the specimen figured has proved it to be a 

 rubbed female specimen of H. reticidatum, Oliv. 



The number of known species has been raised to five by 

 the description of II. griseosericans^Yaumvave, and //. viitiu- 

 tum, Sternberg. A co-type of tiie former is in the British 

 Museum and I have seen a second co-type in the collection 

 of Dr. Sicard. I have also been allowed to examine the 

 type of //. 77iinutum, which is now the property of Herr H. 

 Prell, and that of //. reticulatum, Oliv., from the Dufresne 

 collection in the Edinburgh Museum. 



I have examined altogether ^considerably more than a 

 hundred specimens of the genus in order to obtain as clear 

 an idea as possible of its specific differentiation. All the 

 specimens fall readily into two groups, which have numerous 

 and well-marked differ^'uces ; but within these two groups 

 subdivision is much less easy, owing to the considerable 

 variation in shape and sculpture and the absence of any 

 important structural differentia. 



In the first divi.sion, represented by the first-described 

 species, H. reticulatum, Oliv., the elytra are not abbreviated, 



