S4 PTEKOPrs. 



oniatus, auratus {Ft. liypomelanus groiip) ; (5) Pt. moJossinns (Pf. 

 Joiiihocensls group). 



The relatively large number of species is chiefly clue to the spread- 

 ing of a few fundamental ty{)es over numerous widely scattered 

 groups of islands, and their consequent differentiation into many, 

 but often only slightly differing, forms. The fauna falls naturally 

 into three classes of forms — those which are the extreme eastern 

 offshoots of essentiiilly Austro-Malayan groups, those belonging to a 

 group which, though essentially Polynesian, is also represented in 

 the indo-Malayan Archipelago, and the peculiar Polynesian types. 

 To the first category belong P<. ornatus (Xew Caledonia) and cmratus 

 (Loyalty Islands), only slightly modified representatives of the 

 Avidely distributed but chiefl}' Austro-Malayan hypomelonns group, 

 which here finds its extreme south-eastern limit ; and Pt. molos- 

 st/i?«s (Caroline Islands), a member of a group which now numbers 

 only four species, but formerly must have had as wide a distribution 

 as the Jiifpomelanns group, since its surviving forms are spread 

 over the Carolines, Lesser Sunda Islands, and Mascarenes. To the 

 second class of forms l>elong the five speciea of the Pt. pselaphon 

 group, inhabiting the Bonin and Volcano Islands { pstlaphon), 

 Pelew Islands (piJosus), Carolines (insnhfris and pTuwctphalus), and 

 (?) Vanikoi-o (ijfi'x'j-f '(?«<!««) ; this group is represented also in the 

 Philippines (I e%i copier us). All the remaining ten species, the genuine 

 Polynesian fauna, are clearlj' modifications of only two types, the 

 mariannus and samoensis tj'pes. The Pi. mariannus group, seven 

 closely interrelated species (with an eighth species, Pt. loorlwensis, 

 in the S. Liu-kiu Islands), is distributed over practically the whole 

 subregion, so far as inhabited by the genus, from the Pelew and 

 Marianne islands south-east to Tonga, Tiji, and Samoa ; it is 

 extremely closely connected with the Itypomdanus group, scarcelj' 

 more than its Polynesian representative, Pt. admiralitatum forming 

 a transition between the two groups. The Pi. samoensis group, 

 three sharply differentiated species, is entirely South Polynesian 

 (New Hebrides, Fiji, Samoa) ; but the group is undoubtedly a modi- 

 fication of the lonihocensis type. 



The subjoined geographical review of the species and sub- 

 pecies is based almost entirely on material examined during the 

 preparation of this C!atalogue. 



1. Malagas)! liecjion, 



Madagascar. — Pf. rufns rn/iis (northern and central), nifus princcps 



(southern). 

 Comoro l.slands. — Pf. comom/sis (generally distributed), livuit/stonei 



(Johanna I.). 

 Aldabra. — Pt. aldalircmU. 

 Seychelles. — Pt. sci/cheUeusis. 

 Mauritius, Reunion. — Pt. niger, sahnic/cr. 

 Eodriojiie?:. — Pt. rocJriccnsi^. ... 



