240 [October, 1896. 



probably some other cause added. It is possible this added cause 

 may be the fact that, whereas the sexes of one species have the same 

 food, allied species, as a rule, have different food. But, on the other 

 hand, it is equally possible to contend, that the supplemental difference 

 of specific from sexual distinction is to be found in aboriginal consti- 

 tution ; though this last point possibly does not amount to more than 

 that the said supplemental distinction is not of very recent origin. 



Plagithmtsus vitticollis, n. sp. 



Niger, pedibus nigro-rufis, femoribus ex parte majore rufis ; prothorace 

 opaco, vittis quatuor latis ochraeeis ; elytris ad humeros latis, guttis albidis 

 irregularibus ornatis, ad latera posterius parcissime punctatis . 



Long., 11 — 18 mm. 



Front of head with a good deal of white pubescence. Thorax dull, covered 

 with tomentum tliat quite conceals the very dense fine sculpture ; the four yellow 

 stripes broad and very distinct ; no smooth space at the sides ; the anterior tuber- 

 osity strongly elevated, the posterior slightly elevated and marked with two 

 transverse lines. Scutellum broad and short, truncate. Elytra rather closely 

 punctured at the base, the lateral portions nearly smooth, marked with very 

 conspicuous little patches of white pubescence irregularly placed, and not agreeing 

 on the two sides. Femora red, black towards the tip ; the rest of the legs nearly 

 black. The spots of yellow pubescence on the meso- and meta-sternal side-pieces 

 Tery definite and distinct. 



The species varies in colour, the external parts of the elytra being sometimes 

 yellowish or red. 



Kilauea, Hawaii ; August, 1895. Ten specimens ; on " Akala " 

 (Eubus). 



Var. longulus. A single individual was obtained at Olaa, Hawaii, 

 in June, 1895, from another tree, "a large, smooth, light-barked tree, 

 whose trunk is always excised into an angular form ; the Plagithmi/sus 

 burrows in the solid trunk." I doubt this being distinct from P. 

 vitticollis ; it is of more elongate form, the femora are black, except at 

 the base ; the clothing of the thorax is less dense, and its posterior 

 tuberosity is perhaps rather more elevated. 



Plagithmtsus Newelli, n. sp. 

 Nigro-rufus, thorace dorso incequali, dense minute punctata, ohaolete bi- 

 vittato, titrinque quasi carinulato, lateribus politis ; elytris ubique dense 

 punctatis, guttis albidis irregularibus ornatis. Long., II mm. 



Although somewhat similar to P. vitticollis, this is very distinct, the elytra 

 being densely punctate, and the thorax very peculiar. The flanks are shining but 

 minutely punctate ; the dorsum is densely punctate, and is limited by an irregular 

 line, along the inner margin of which there is a little flavescent sctosity ; the 



