HETEROMERA, MALACODERMATA, ETC. 



9] 



Melanesia and Polynesia. The number of genera represented, however, is but 

 small, and the differences between them are not always very readily perceived. 

 The number of species is considerable for an insular fauna, though in appearance 

 they resemble one another very closely. The difficulty of recognition, and the 

 considerable range in distribution of many of the species have inevitably 

 resulted in considerable confusion in determination, and unfortunately, apart 

 from Seidlitz's revision of the whole family in Naturgeschichte der Insecten 

 Deutschlands (1899), no revision of the Pacific fauna exists. 



Five species were recorded from Tahiti by Fairmaire (Rev. ZooL, pp. 454- 

 457, 1849), under the genera Nacerdes and Selenopalpus, all but one of which 

 have since been recorded by Schenkling from Samoa (Arch. f. Nat., Bd. 88, 

 A. 10, p. 153, 1922.) 



The three very similar genera may be distinguished as follows : 



1. (2) Mandibles simple at apex, projecting considerably beyond labrum, 



and overlapping when closed . . . .... Sessinia Pasc. 



2. (1) Mandibles bifid at apex, scarcely projecting beyond labrum, inter- 



locking when closed ........ 3 



3. (4) Palpi simple in both sexes ; only 5 visible abdominal segments in $ ; 



sexes scarcely distinguishable . . . . . Ananca Fairm. 



4. (3) Last joint of maxillary palpi in $ excavate on outer side towards 



apex ; 5th abdominal segment of $ abbreviated, exposing 



genital armature ........ Pselaphanca Blair. 



34. Ananca kanack Fairmaire (Text-fig. 8). 

 Rev. Zool. (2), I, p. 454, 1849 (Nacerdes). 



Sessinia kanak Fairm., Schenkling, Cat. Col. Oedem, p. 33, 1915. 



Upolu : Apia, 14.ix.1923, 15 examples (Swezey and Wilder). 



Tutuila : Pago Pago, 14.ix.1923, 1 example (Steffany). 



Readily recognisable on account of its large size (about 18 mm.), in con- 

 junction with the form and coloration of the thorax, which is depressed dorsally, 

 with a narrow median strip and a lateral strip on each side bluntly raised, these 

 raised areas being fuscous. The sexual differences are very slight, the 5th 

 ventral segment being entire, bluntly rounded at the apex and usually closely 

 applied to the pygidium. If these be separated, the 6th ventral in the is seen 

 to be flat, with a deep median emargination. Fairmaire remarks that, among 

 his four species of Nacerdes, he has not been able to find a single 



The British Museum possesses specimens from Tahiti, Fiji, the Solomon 



