The President's Address. By Prof. P. Martin Duncan. 179 



treated his subject zoologically, but also morphologically. Of the 

 male of this species, Dr. Hudson states, the whole range of the 

 Kotifera does not contain a more curious or more beautifully 

 transparent creature; it may be 1/30 in. long, and is a slow 

 swimmer ; yet it is so transparent that it is almost invisible to the 

 naked eye. Under the Microscope it looks like a many-pointed 

 bubble of glass. This male has no digestive organs, and nature in 

 compensation has given him some stored material for his nutrition. 

 Dr. Hudson gives drawings of the tortuous threads and tags that 

 are so constantly present in Kotifers. He delineates the sper- 

 matozoa and the central portion of the ovary of the female with 

 maturing germs. 



Our Secretary, Professor Bell, has given us some accurate figures 

 and descriptions of the spicules of the body- wall and suckers of the 

 Holothurians named Cucumaria hyndmanni and G. calcigera, and 

 in concluding his essay he remarked that the greatest care is 

 required to preserve the parts of typical specimens if they are to 

 continue to be of value. The spicules of one of these species, G. 

 calcigera, were carefully studied by my colleague, Dr. Percy Sladen, 

 and published in our work on the Arctic Echinodermata. On ex- 

 amining our figures, plate I. figs. 6, 7, and comparing them with 

 those of Professor Bell, it would appear that there must be altera- 

 tions proceeding in the spicules during the preservation of the 

 specimens. Possibly the methods employed to exhibit the specimens 

 may modify them. The microscopic details in our figure of a 

 small spicule in profile (fig. 7) are more ample than those in our 

 Journal (vol. iii., plate VIII., fig. 2a) and it would appear from 

 our figure (6) of spicules from the superficial layer in situ, that 

 there must be variation in those structures in difierent individuals. 



Mr. Conrad Beck has described some very interesting Clado- 

 cera from the English Lakes in our Journal, and his figures of them 

 are most praiseworthy. It is to be hoped that this is by no means 

 the last of his communications. He has chosen a subject full of 

 interest to the naturalist as well as to the investigator of the great 

 movements of the crust of the earth. The relation which some of 

 these Cladocera bear to marine forms is obvious, and Loven, 

 Agassiz, and myself have pointed out their occurrence in positions 

 which indicate their entry before the country assumed its present 

 physical aspect. Their occurrence in the Swiss and Norwegian 

 lakes is very antagonistic to the idea of the excavation of these 

 areas by ice. 



The Diatomaceae have been the subject of some very interesting 

 researches. Methods of making fine sections of these delicate 

 sihcious bodies have been suggested and carried out with some 

 success. It could hardly be expected that a year could pass 

 without some further researches on the cause of the movement 



