chap, xiii.] THE AUSTRALIAN REGION. 407 



Acherusia has 2 species in Brazil, 1 in Australia. These re- 

 semblances may probably have arisen from intercommunication 

 during the warm southern period, when floating timber would 

 occasionally transmit a few larvae of this family from island to 

 island across the antarctic seas. When the cold period returned, 

 they would spread northward, and become more or less modified 

 under the new physical conditions and organic competition, to 

 which they were subjected. 



We now come to the very important group of Longicorns, in 

 which the Australian region as a whole, is very rich, possessing 

 360 genera, of which 263 are peculiar to it. Of these about 50 

 are confined to the Austro-Malay Islands, 12 to New Zealand, 

 and the remainder to Australia proper with Tasmania. Of the 

 genera confined to, or highly characteristic of Australia, the 

 following are the most important : — Cnemoplites, belonging to 

 the Prionidae ; Phoracantha, to the Cerambycidse ; Zygocera, 

 Hebecerus, Symphyletes, and Rhytidophora, to the Lamiida?. 

 Confined to the Austro-Malay Islands are Tethionea (Ceramby- 

 cidse) : 1 mesisternus, Arrhenotus, Micracantha, and Sybra 

 (Lamiidae) ; but there are also such Malayan genera as Batocera 

 Gnoma, Praonetha, and Sphenura, which are very abundant in 

 the Austro-Malay sub-region. A species of each of the Austra- 

 lian genera, Zygocera, Syllitus, and Pseudocephalus, is said to 

 occur in Chili, and one of the tropical American genus, Hamma- 

 tochccrus, in tropical Australia ; an amount of resemblance 

 which, as in the case of the Buprestidae, may be imputed 

 to trans-oceanic migration during the Southern warm period. 

 This concludes our illustrations of the distribution of some of 

 the more important groups of Australian insects ; and it will be 

 admitted that we have not met with any such an amount of 

 identity with the fauna of Temperate South America, as to 

 require us to modify the conclusions we arrived at from a con- 

 sideration of the vertebrate groups. 



Land-Shells. — The distribution of many of the larger genera 

 of land-shells is very erratic, while others are exceedingly re- 

 stricted, so that it requires an experienced conchologist to 

 investigate the affinities of the several groups, and thus work 



