Appendix B. 373 



of a railway, is subjected to the dust from" 1 loading and unload- 

 ing of the waggons, and to the deleterious fumes of a range 

 of brick-kilns within a dozen yards or so, and is generally 

 covered with a sprinkling of soot from the neighbouring 

 factories. It is, further, the playground for the children of the 

 vicinity to sail their small boats upon. In spite of all these 

 apparent disadvantages against the ostracoda, I seldom fail 

 to obtain a fair gathering of them in this small patch of water, 

 whether in summer or winter. Their survival under all these 

 circumstances may be due to the fact that what is harmless 

 and healthful to them may be death to their enemies. The 

 Cypridce proper are seldom if ever found in very deep water, 

 but mostly amongst the vegetation, while the Candona are met 

 with at greater depths. In Loch Lomond I have found them 

 at a depth of forty fathoms. Although these small crustaceans 

 appear to be greatly more abundant on the plains than on the 

 mountains, Dr. G. S. Brady records Cypris cinerea, C. compressa, 

 C. striolata, etc., from a pool near the summit of Mickle Fell, 

 in Yorkshire, at an elevation of two thousand feet. 



"From the foregoing, it is evident that the abundance of 

 these organisms in one place cannot always be taken as an 

 index of their profusion in another, although the two may be of 

 quite similar appearance. In the one, these forms of life may 

 be swarming ; in the other, absent or nearly so. So little can 

 we depend upon apparent similarity in this respect, that, in 

 collecting, it is well to make trial of even the most unlikely 

 spots, and, although we may meet with frequent disappoint- 

 ments, we shall, on the other hand, often find what we shall 

 deem prizes where they are least expected." 



As to " time for collecting :" "The best time for collecting 

 these organisms is in summer, as they are then met with in the 

 greatest abundance. There can be little doubt that heat is 

 conducive to their increase and development. Dr. G. S. Brady 

 states that he has found them in the water of mill cooling-ponds 

 at a temperature of 100 Fahr., and the water might at times 

 be even hotter." 



" Mode of Collection? The suitable net attached to a jointed 

 rod has been already described. 



"To have the full benefit of the gathering for ostracoda, it 

 is necessary to take some of the mud, which in most cases can 



