PRESERVATION OF THE HYDRQIDA. 145 



section of coast, the results of which were embodied in a report. 

 The shore collecting was apparently confined to one spot, from 

 which but one hydroid, and that the ubiquitous Sertularia pamila, 

 was recorded ; yet a quarter of a mile farther east is an excep- 

 tionally prolific hunting-ground at low tide, where at least a 

 dozen species of hydroids may be taken. All this points to the 

 fact that wherever the hydroid-hunter elects to collect he must, 

 as a preliminary, first ascertain that he has found the hydroid 

 ground. When he has satisfied himself that he has done so, then 

 collecting may begin in earnest. 



It is too readily assumed that only those shores are good for 

 hydroid-hunting upon which rock-pools occur. My experience 

 leads me to protest against this assumption, for I have often 

 had much better collecting on shores strewn with large fucus- 

 covered boulders than in some rock-pool districts. Rock-pools do 

 not necessarily imply the existence in them of hydroids, not even 

 when they are clean, sanitary abodes. The rock-pools at Sid- 

 mouth are excavated in Permian sandstone at the base of cliffs 

 500 ft. high, composed principally of Keuper marl, and in the 

 early summer are lined, as is everything in them, with fine 

 mud, the result of the red marl falling from the cliffs during 

 winter and being washed into the pools. This should make 

 hydroid life impossible, but it does not ; they seem to thrive in 

 it (I sometimes think upon it), and cleaning them for the 

 microscope thoroughly disheartens one. Last autumn I was 

 collecting in South Devon, where the cliffs are composed of 

 hard conglomerate, giving fine clean rock-pools. One rock-pool 

 near low-water mark especially attracted my attention. Filled 

 with clear, limpid water, its sides draped with seaweeds, every 

 condition seemed perfect for hydroid life, and yet not a single 

 specimen was found in it. I satisfied myself of this by abso- 

 lutely cleaning the pool out, examining every piece of seaweed, 

 as I removed it, in a small tank of water, then going carefully 

 over the sides and bottom of the pool with a lens of large 

 diameter. It is little discrepancies like these that both try and 

 puzzle the shore collector. 



Hincks has given advice upon shore collecting that cannot 

 well be improved upon, and is as precise as such advice can 

 be. He recommends lying at full length when collecting, and 

 however objectionable this may seem to be in theory, it is 



