152 Mr. G. J. Arrow on the 



Stypotrupes endymion, Oliv.j of whicli the original examples 

 are in tlie British Museum, is a Strategus with the head of 

 the male peculiarly modified, the end of the clypeus being 

 produced upwards as a broad lamina. Burmeister, the author 

 of the genus, was entirely mistaken as to its affinities, and 

 the genus is an especially unsatisfactory one, being based 

 upon the present species, the totally different one for which 

 I have already made the genus Clyster, and a third, of which 

 only a fragment is known, and which, if, as supposed, it is 

 Oriental, is certainly also very different. A female of 

 a5^. endymion in the Museum was apparently brought by 

 Darwin from the Galapagos Islands, and there can at least 

 he no doubt that the insect belongs to the American fauna. 

 The female shows so intimate a relationship to Strategus that 

 I think the advisability of treating the species as a member 

 of that genus will hardly be disputed. A difference is 

 generally found in the sculpture of the propygidium in the 

 two sexes of Strategus, and this is accentuated in S endymion., 

 the male of which has rather fine stridulatory ridges, which in 

 the female are represented by very coarse scattered granules. 



By a process of elimination the unknown S. telamon, 

 Burm., is now left alone to represent the genus Stypoti'upes. 

 Its identity can only be established by examination of the 

 fragmentary type in M. Oberthiir's collection. 



Enema pan, Y., is a remarkable polymorphic species, con- 

 cerning which perplexity still prevails. Bates, in the 'Biol. 

 Centr.-Americana/ has figured the female form (called 

 titornus by Perty) as a male, calling it the variety Inpercus, 

 Chevr., which is really the reduced male phase. In the same 

 work he expressed a strong suspicion that Enema infundilnhnn, 

 Burm., is a form of this species, but without actually putting 

 them together. Herr Sternberg has described them as two 

 forms of a vanished species, which seems to be a way of 

 saying two species of the closest affinity. It appeal's to me 

 that the evidence is entirely in favour of regartling them as 

 actually conspecific, infandibulum being the extreme phase oi 

 development of the male armature. The two forms occur in 

 the same localities from Central America to South Brazil, 

 but, abundant as they are, only a single form of female is 

 found. I have examined the male genitalia, and found no 

 difference. 



It is very remarkable that, whereas in the typical form 

 every grade of armature is found, from the highest to a 

 degraded form little distingiiislu d from the fcnuilc, no iuttr- 

 uiediates connecting it with the differently armed inj'undibuluni 



