Conference on Monday, July 23, 1883. 



Mr. John Tremayne in the Chair. 



CRUSTACEANS. 



I HAVE been requested to read to you a short Paper on 

 " Crustaceans." 



The Crustaceans are a large class of articulated animals 

 whose distinguishing feature to the mere outside observer 

 is that they are covered over the whole of their bodies and 

 legs by a shell of more or less hardness, and it is this total 

 covering in a coat of mail which mainly sets them apart 

 from other classes of animals. 



They are found on the land, in the fresh water, and in the 

 salt water : and, amongst themselves, are divided into two 

 distinct varieties, ie., the " Sessile-eyed "crustacean, in which 

 the eye lies flat in its socket, with just the amount of 

 mobility and scope of vision which the eyes of most animals 

 have ; and the " stalk-eyed " crustaceans, in which the animal 

 has a certain limited power of projecting its eye, at its own 

 will, beyond its socket or immediate surroundings, and so 

 obtaining a considerably enlarged sphere of vision. 



With the single exception of the common river cray- 

 fish I shall confine myself to-day to the crustaceans whose 

 home is in the sea. 



Among these I shall very curtly dismiss the "Sessile- 



B 2 



