26 



THE CONCHOLOGIST. 



specimens of a dwarf form of Linuuea 

 peregra abound — all thickly coated with red 

 oxide of iron of so exactly the same colour 

 and texture as the surrounding red mud as 

 to be hardly distinguishable ; in bright sun- 

 shine their presence is proclaimed by the 

 long ruts or trails left as they actively 

 plough their way through the yielding red 

 mud ; when touched the animals immedi- 

 ately retire into their shells and remain 

 quite still. 



In the Lathkiln, Derbyshire (a clear stream 

 highly charged with carbonate of lime in 

 solution), I observed a small form of Linuuea 

 peregra roughly coated with this so as to 

 be undistinguishable from the stony bottom 

 where all else is similarly covered — a large 

 specimen of the variety labiata living at 

 the bottom of a hole made by a cow's 

 hoof was enshrouded in conferva. 



Planorbis contortiis living among the rich 

 black mud at the roots of flags in the 

 Brent, at Neasden, is stained the same 

 colour, although specimens from other pai:ts 

 of the stream are quite clean. Planorbis 

 complanatus is sometimes encrusted with a 

 close green conferva hard to remove. 



Planorbis corneiis — Several large and old 

 specimens covered with conferva in the 

 Leg of Mutton pond — others from this pond 

 are tinged a rusty red with oxide of iron. 



No doubt the presence of mud and 

 growth of weed are favoured on these shells 

 by their sluggish habits, but it is significant 

 that all the conferva coated specimens I 

 have found were large and old, and doubt- 

 less owed their longevity to its protection. 



ON THE BURROWING HABITS OF THE 

 GENUS TESTACELLA, CUVIER. 



By C. D. HoRSMAN, B.A. 



HAVING been much interested in the 

 observations of Messrs. L. E. Adams, 

 I W. E. CoUinge, F. Rhodes, and B. Tomlin, 

 j which have lately appeared in the Science 

 Gossip and Naturalist, I venture to forward 

 some observations of my own on the above 

 genus, which ditfer slightly from those of the 

 above-named writers. 



In speaking of T. haliotidea, Mr. Collinge* 

 says he has found it at a depth of from four to 

 five feet, and mentions that Mr. Quilter found 

 T. scutuluni at a depth of eighteen inches. 

 Dr. Jeffrey's mention of T. niaugei not being 

 from personal observation is open to question. 

 Mr. Tomlinf says he has found this last- 

 named species from six to twelve inches 

 below the surface. 



I have carefully observed these three species, 

 j but have no record of ever having found 

 I any of them below twelve inches, and in the 

 majority of cases only five or six inches below 

 the surface. I have never noticed any 

 " clean cut hole, " as mentioned by Mr. 

 Tomlin ; all I have observed have generally 

 commenced to burrow by burying themselves 

 in the loose surface soil. I should like to 

 know if they have ever been observed to use 

 the burrows of earthworms, as if so, they may 

 be able to reach a great depth, but this can 

 hardly be termed burrowing as we understand 

 the word in regard to the mollusca. It will 

 be as well, perhaps, to mention that my 

 experiments were carried out on a fairly heavy 

 soil. In future observations it would be 

 useful to state whether the soil is clayey, 

 sandy, compact, or loose. 



* Observations on the burrowiMg habits of certain land and fresh, 

 water Mollusca. Naturalist, March, 1891. 



t Burrowing Molluscs. Xatiiralist, April, 1891. 



