390 PEOCEEDINGS OF THE SOCIETY. 



burnt it in an argand burner ; if this was correct, he should be sorry to 

 be in the room while the light was going. Most people knew what an 

 unpleasant smell and smoke were given out when a burner was not 

 properly adapted for the consumption of acetylene. 



The President said that in giving a lecture some years ago at 

 Peterborough, acetylene was used for the lantern. The light was very 

 excellent, but the heat was so intense that it cracked the cold lens of 

 the lantern, and after this his slides appeared with a black flaw across 

 the object. When staying this year at an hotel in Italy, where acetylene 

 was used, the gas gave an excellent light, but it needed great attention, 

 a man having to clear out tho burners almost nightly, the acetylene 

 frequently emitting a quantity of black smoke from imperfect com- 

 bustion. He believed, also, that great complaints had lately been made 

 about its use by the drivers of the London General Omnibus Company, 

 on account of the powerful odour of garlic emitted from the lamps. 



Mr. D. J. Scourfield, being called upon by the President to give 

 some explanation of the exhibition of Fresh-water Entomostraca which 

 he had arranged in the room, said that he had not attempted to make 

 this an exhibition of all the orders of the Entomostraca, neither had he 

 followed a scientific classification in the arrangement of the specimens, 

 but had confined himself to the Cladocera, and to the illustration of the 

 various habits of life and powers of movement shown by these animals, 

 ranging from the free-swimming forms found in lakes to those which 

 simply crawled about in or on the mud. In addition to their trans- 

 parency the characteristics of the lake or " plankton " forms were : great 

 development of the swimming organs (Leptodora hyalina *), or the pos- 

 session of long spines and other outgrowths (Daphnia Jcahlbergensis, 

 Bosmina longirostris, Bythotrepnes longimanus), or the production of a 

 mass of jelly serving probably as a float (Holopedium gibberum). Next 

 to these came the species which might best be described as the continu- 

 ally hopping forms. They could not cling to weeds and yet were not 

 adapted for life in the open water of lakes. They had to maintain 

 themselves in the water by constant and laborious movements of their 

 comparatively weak swimming antennae (Daphnia pulex, D. magna). 

 Then followed the species which did not swim unless they were obliged 

 to, for they possessed the means of attaching themselves to weeds, &c, 

 and made full use of their powers. The attachment was brought about 

 in various ways. In some cases (Simocephalus vetulus) minute hooks on 

 two of the antennal setsfi enabled the animals to cling to solid objects in 

 the water; in others (Oamptocercus rectirostris, Pleuroxus aduncus, Chy- 

 dorus sphsericus), the clinging was brought about by hooked set® on the 

 feet; and in yet other cases (Graptoleberis testudinaria') the attachment 

 was made apparently by the setae on the ventral margin of the shell. 

 There was one of these clinging species (Seapholeberis mucronata), which 

 had even discovered how to make use of the surface film of water for 

 support. Lastly, there were the bottom and mud-loving species, some 

 of which could indeed swim when necessary (Macrothrix laticornis, 



* The species mentioned are those included in the exhibition; they are of 

 course, as a rule, only representatives of their respective groups. 



