COLEOPTERA 



93 



red, half black. This variety is very common in this species but does not occur at all 

 in either of the two allies though each of them is variable to a greater {P. lamarckianus) 

 or less {^P. darwitiianus) extent as to the redness and blackness of the legs. P. varians 

 is almost trimorphic as regards the colour of the legs, but the three forms are not 

 completely distinct, and one of them is very much rarer than the other two. 



Of P. daj'2ui7tiamis I have not a large series before me, but Mr Perkins examined 

 a large number of specimens of this species captured by Mr A. Koebele and tells me 

 that the legs are always red or nearly so in it'. 



Thus as regards the character here considered we find that P. aequalis is 

 dimorphic, that P. varians is imperfectly trimorphic, and that P. darwinianus is only 

 slightly variable. 



Very little information is available as to local variation. We have not received 

 any one species of Plagithmysus from more than one locality in any considerable 

 number ; the specimens we have received lead me however to anticipate that consider- 

 able local difference in the variation exists. As an example I may mention that the 

 five specimens of P. aequalis — a species confined to the island of Kauai — found at 

 Waimea in April cannot be quite matched by any specimens of the large series found at 

 Makaweli in January and February. Whether greater information as to local variation 

 would lead to the union of some of the species at present treated as distinct, is a point 

 on which I am not at all positive. 



I may however point out that the three closely allied species I have already 

 mentioned as being found in one locality have there each a different food-tree. In 

 other words they are segregated by food though not by locality. 



The two closely allied species, P. blackburni and P. dai'wiitiamis, exhibit the 

 converse of this. Though both are found in the island of Hawaii and have the same 

 food-tree they have not yet been found in the same locality. Each of these species has 

 however as yet only been once or twice met with. It would be very interesting 

 to know whether they ever occur together, and if so whether they still remain 

 distinct. 



In connection with this I must not omit to call attention to the peculiar case of 

 P. vitticollis with its var. longulus, and of P. bishopi with its V2S . gracilis. In the case 

 of these species the variety and typical form inhabit either different localities or different 

 trees. We know however but little about these two species, and it is possible that 

 these "varieties" may be incipient species, or even closely allied, but actually distinct 

 forms. At present it holds good that all the forms I have treated as distinct species 

 are segregated either geographically or by food : and this also applies to the two 

 varieties just mentioned. 



' A small series only of P. lamarckianus having been procured I do not mention its variation here, but 

 may refer the reader to p. no. It appears to be different from either of the other species as regards 

 the character under discussion. 



13—2 



