FEBRUARY. 



placed that each plate overlaps the one behind. This 

 jointing of the thoracic portion gives great flexibility to 

 the body, while at the same time the soft parts underneath 

 are protected by a coat of mail. Behind the thorax come 

 six smaller joints, the last of which is very small and ends 

 in a sharp point ; these form the abdomen. If the creature 

 is turned over on its back we notice that there are seven 

 pairs of similarly formed legs, one underneath each of the 

 thoracic segments ; while under the abdomen there are 

 five pairs modified into plates and acting as gills or breath- 

 ing organs, while the sixth pair is also plate-like, but the 

 plates project out beyond the last segment, like fans. In 

 all the Crustacea the ways in which the different appen- 

 dages of the body are modified are endless ; in some they 

 act as organs for masticating the food or catching the prey, 

 in others for defence, walking, swimming, burrowing, 

 breathing, or in connection with sexual functions. Thus 

 if the wood-louse happens to be a gravid female it will be 

 found that to each of the thoracic legs there is attached 

 i broad flap-like piece, and these seven pairs of flap-like 

 processes form a brood-pouch within which the animal 

 carries a large number a hundred or more of eggs. 



It would be interesting in connection with these creatures 

 to show the gradual steps, as exhibited in the life-histories 

 of their numerous relatives, by which a marine water- 

 breathing animal has come to be terrestrial and chiefly 

 air-breathing, but this would take us quite outside the 

 limits of our field work, and the temptation to indulge in 

 what is a laboratory question must be restrained and for 

 the present set aside. The common wood-louse of our 

 gardens is not a New Zealand species at all ; it is a common 

 European form (Porcellio Icevis) which is found in most 

 temperate regions of the world where Britons have settled. 

 It has 110 doubt been brought across the seas along with 

 plants or roots. I have gathered this species in Melbourne 

 and in Hobart, as well as in many parts of this colony. 



There is one other species of crustacean * to be found in 



* Orchestia sylvicola. 



