March, 190".] THE TICTORIAN NATURALIST. 221 



life were learnt and passed on to succeeding generations. 

 He said that the shore and shallow-sea fauna was the 

 original one, whence have been derived, on the one hand, 

 the deep-sea fauna, and, on the other hand, the fresh- 

 water and terrestrial faunas. No other environment pos- 

 sessed such a diversity of kinds of animals living within 

 narrow limits. When contrasted with a freshwater or 

 land fauna, it was easily seen that, in either of these, 

 there was a much greater uniformity. 



With the aid of a fine series of lantern slides, he made 

 comparison of different animals living inland with allied 

 forms found that day on the shore. It was seen that, with 

 the exception of the echinoderms, to which sea-urchirs, 

 starfish, and sea-cucumbers belong, all the larger groups 

 of invertebrate animals, such as sponges, coelentera, seg- 

 mented and unsegmented worms, crustaceans, insects, and 

 molluscs were represented by allied forms in our inland 

 fresh waters. 



In the explanation of the structure and life-history of 

 the hydroid zoophytes, belonging to the group Coeleitiera, 

 the audience was much interested with the remarkable 

 alternation of generations which they possess, and received 

 a clear exposition, by comparison of the free swimming 

 medusa with its parent, the colonial form (often called 

 a seaweed), and with the simple naked hydra inhabiting 

 our fresh waters. Others of the Coelentera — the sea- 

 anemones and corals — were briefly referred to and com- 

 pared with the zoophytes, and, although so unlike on a 

 casual observation, it was seen that on close examination 

 they all possessed a similar ground-work of structure. 



In the crustaceans, it was shown that the common shore- 

 hopper possessed very close relations living inland in 

 damp forest country, where two species existed, one called 

 Talitrus sylvaticus, and another undescribed species. 

 These terrestrial forms were compared with their nearest 

 marine relatives, and it was seen that certain adaptations 

 in structure existed — particularly in the organs of loco- 

 motion and the breathing apparatus — to fit them for their 

 altered environment. It was also said that several species 

 inhabited our fresh waters, but were not so closely related. 

 Speaking further of the Crustaceans, the lecturer said 

 that we possessed in our mountain streams remnants of an 

 archaic fauna, several species of which were blind, and 

 were of considerable zoological interest. 



