102 NOTES. 



It is exhibitions of this kind that give an impetus to microscopy 

 by interesting persons in the study of the wonders of the semi- 

 invisible. — 



One of the principal exhibits at the Conversazione was that 

 of the Marine Biological Association, showing the different 

 stages in the development of food fishes, and also an inge- 

 nious apparatus by which colour is made to assert itself on the 

 underside of flat fish, and which will probably give a clue to the 

 piebald appearance of many fish which has puzzled investigators 

 so long. Considering the almost national importance of the work 

 done by the M.B.A., it is to be regretted that it is not sufificiently 

 known to be appreciated at its proper value. To those of our 

 readers who are interested in the study of marine life, we 

 would call attention to the advantages of the association. The 

 M.B.A. issue a price list of Marine xA-lgae, and of Zoological 

 specimens (ranging from Protozoa to Fishes), which are supplied at 

 an extremely cheap rate, and we strongly advise all who would 

 continue their investigations in these subjects to communicate 

 with the Association at their Laboratory at Plymouth. By doing 

 this they will derive the double satisfaction of getting subjects for 

 investigation, and of contributing, in no slight degree, to the success 

 of the Association. 



Speaking of the enormous variety of insect life. Dr. C. V. 

 Riley, in the Bulletin of the U.S. National Museum, No. 39, says : 

 "The omnipresence ol insects is known and felt by all ; yet few have 

 any accurate idea of the actual numbers existing, so some figures 



will not prove uninteresting in this connection Linnaeus 



knew nearly 3,000 species, of which more than 2,000 were Euro- 

 pean and over 800 exotic. The estimate of Dr. John Day, in 

 1853, of the number of species on the globe, was 250,000. Dr. 

 Sharpe's estimate, 30 years later, was between 500,000 and 

 1,000,000. Sharp's and Walsingham's estimate in 1889 reached 

 neaty 2,000,000, and the average number of insects annually 

 described since the pubhcation of the Zoological Record., deduct- 

 ing 8 per cent, for synonyms, is 6,500 species. I think the 

 estimate of 2,000,000 species in the world is extremely low, and 

 if we take into consideration the fact that species have been best 

 worked up in the more temperate portions of the globe, and that 

 in the more tropical portions a vast number of species still remain 

 to be characterised and named, and if we take further into con- 

 sideration the fact that many portions of the globe are yet unex- 

 plored entomologically, that in the best worked-up regions by far 

 the larger portion of the Micro-Hymenoptera and Micro-Diptera 

 remain absolutely undescribed in our collections, and have been 

 but very partially collected, it will be safe to estimate that not 



