XX First Report on Economic Zoology. 



Survey of Group C. 



Protozoa None. 



Porifera None. 



Ccelentera None. 



Echinoderma None. 



Platyhelmia None. 



Nemertina None. 



Nematoda Various eel-worms (Aiigjiilhilidx) hasten decay in plants. 



Chaetopoda The earthworms form surface soil and bury stones on 



the surface, and prepare seed beds, etc., for plants. 



Crustacea None. 



Arachnida None. 



Chilopoda None. 



Diplopoda None. 



Hexapoda Many insects act as scavengers in all parts of the world; 



the larvae of flies (CaUipJiora) feed upon and hasten 

 decay of carrion ; some carrion beetles {Silphidx) \ dung 

 beetles (Copridfc and Dynastidie) ; burying beetles 

 (Necrophonis) also act as scavengers ; humble bees 

 (Bojnbi) fertilise clover, and many other insects act as 

 fertilisers (Trigona and Vanilla, Blastophaga and figs). 



;Mollusca None. 



Tunicata None. 



Pish Fish, especially carp, keep water free from insects and decay- 

 ing matter, and are used for such purposes in reservoirs. 



Amphibia None. 



Reptilia None. 



Birds Vultures, by destroying the flesh of dead animals and man. 



Mammals Rats feed upon carrion, as well as sound food; and also 



jackals and semi-vrild dogs. 



GEOUP D. 



Animals which concern Man as causing bodily injury, some- 

 times death, to him, and in other cases disease, often of a 

 deadly character. 



This large group contains representatives in most of the divisions of 

 the animal kingdom. It may conveniently be divided into two sub- 

 groups, viz., («) animals which cause injury, by direct attack, to man, 

 and (&) animals which cause disease by acting as germ carriers. 



In the former section parasitism plays an important /-die. 



Survey of Sub-group (a) of Group D. 



ANIMALS WHICH CAUSE INJURY, BY DIRECT ATTACK, TO MAN. 



Protozoa Malarial hcemamoebidre, coccidia, Amo&ba coli, and 



Trj-panosoma in the blood. 



Porifera None. 



Ccelentera Jelly-fish, by stinging man when in sea water. 



Echinoderma Spines of Echinus may penetrate the skin. 



Platyhelmia Numerous tapeworms (Cestoda) are parasitic in the 



intestines of man (Txnia solium, Txnia saginata), 

 and in their cystic or hydatid stage in the various 

 organs and connective tissue (Echinococcus liominis). 

 Flukes (Trematoda) also occur as parasites in man 

 {Bilharzia hxmatohium, Distoniuni hcpaticum). 



