96 A Guide to the Zoological Collections in the 



female the abdomen ends in an ovipositor, which has 

 sometimes a poison-gland connected, to form a poison- 

 spine or "sting '\ The metamorphosis is complete. 



The Order, which includes the Saw-flies, Gall-wasps, 

 Ichneumon-flies, Ants, Solitary wasps, Social wasps, Soli- 

 tary Bees, and Social Bees, is illustrated in Cases 930 — 

 97B. The marvellously complex economy of the social 

 Hymenopfera, especially of the Ants, can only be men- 

 tioned here. The communities consist (i) of winged males 

 which are usually short-lived, (2) of winged females, which 

 are usually very few in number, and (3) of a vast number 

 of usually sexually-undeveloped females which may be 

 either winged (Bees) or wingless (Ants), and are known 

 as "workers". Among the ant communities the "work- 

 ers " are sometimes of two kinds — *' soldiers " with large 

 mandibles, and "true workers". 



Practically, owing to the transient existence of the 

 males and the paucity of the sexually-perfect females, a 

 community usually consists of a "Queen" and a horde of 

 "workers", with larvae and pupae. 



PHYLUM V OF THE COELOMATA. 



ECHINODERMATA. 



[Sasteru fflalUas^s 17—36]. 



The members of this phylum are characterised by the 

 radial symmetry of the body. It is only in some of the 

 atypical Holothuroidea that bilateral symmetry occurs. 



The Echinodermata form a very definitely circumscribed 

 group, and their relations to the other great groups are 

 by no means agreed upon. 



The Echinodermata are marine animals usually of a 

 quinque-radial or five-rayed star-shape and covered with a 

 skin which is always thick and stout and is often so 

 impregnated with lime-salts as to form a rigid stony case. 

 For further protection the hard stony integument is often 



