Relations of the Neio-Zealand Fauna. 91 



is not surprising when we rememljer tliat this genus existed 

 during the Lower Silurian period ; but it is interesting as af- 

 fording us the chie hj which other similar anomalies may be 

 explained. 



The New-Zealand Tunicata are as yet but little known. 

 The genera Ascidia, Bolfem'a, and Botryllus are only found in 

 Europe and North Amei'ica. DoUohim denticitlatam is found 

 at the Molucca Islands. 



Of the Polyzoa I am acquainted with eighty-nine species, 

 of which thirty-one have been found nowhere else as yet ; but 

 it is probable that their range is very imperfectly known. 

 Twenty-three of our species are found in European seas, while 

 the intervening tropical seas appear to be almost destitute of 

 this form of life. The chief point of interest in our Polyzoa 

 is the great development of the massive species of Cellepora 

 and of the coral-like family Idmoneidfe, which recall to mind 

 the crag formation of England. Indeed one of our species, 

 Hornera striata, is found fossil in the Crag ; it is, however, 

 also found fossil at Oraki, near Auckland, in beds of still older 

 date. Considering how little attention has been paid to our 

 Polyzoa, the number of known species indicates a rich fauna ; 

 and, indeed, the entire class seems to be more abundant in the 

 southern than in the opposite hemisphere, and, like the petrels, 

 contains many forms quite unrepresented in the north. 



Insecta. 



No New-Zealand naturalist who has collected insects on 

 however small a scale in Europe can, I think, fail to be struck 

 with the paucity in New Zealand, not only of species, but, in 

 some orders, of individuals also. It is remarkable that in this 

 country, w^hose indigenous warm-blooded animals are limited 

 to birds and bats, on entering the bush, instead of finding the 

 masses of decaying wood and leaves swarming with life, we 

 find hardly a living creature*, while at the same time we are 

 attacked by myriads of bloodthirsty mosquitos {Culex acer). 

 It would certainly seem that abundance of food does not pro- 

 duce abundance of individuals in some orders (e. g. Coleoptera) ; 

 neither does an absolute dearth of food in the imago state pre- 

 vent the increase of individuals in others [e.g. Diptcra). The 

 swarms of sand-flies {SimnJium ccecutiens), also, that greet us 

 on the coast from the North Cape to tlie Bluff, where could 

 they possibly have found food before the advent of man ? 

 Where, indeed, do they find it now in sufficient quantities ? 



• "Mj experioncc in this reppoct in New Zealaml is very (lifForent from 

 that of ]Mr. Wallace in Singapore and Borneo, but similar to his in Celebes 

 and Ceram. 



