DISTRIBUTION IN DEPTH 



153 



rare Panopcea Norvegica are swallowed, and ejected again witli 

 eroded surfaces. The haddock swallows shells still more indis- 

 criminately, and Mr. M'Andrew has found great numbers of 

 rare Pectens in them, but generally spoiled. The cat-fish and 

 skate break up the strongest shell-fish with their teeth — account- 

 ing for the many angular fragments met with in the dredge, 

 and in recent deposits. 



The following are examples of shells obtained from great 

 depths : — 



Preserving molluscous animah for examination. 



"When shell-fish are killed by sudden immersion in hot water 

 or strong spirit, great and unequal contraction is caused, d s- 

 torting the muscular parts and rupturing the membranes. 



Experiments have yet to be made for the discovery of means 

 whereby these and other marine animals may be paralysed and 

 killed, without altering the ordinary condition of their organs.* 



Glycerine is the best medium for preserving such objects as 

 the univalve shell-fish, intended for the examination of their 



* The brittle-stars (Opkwcoma) are killed by sudden immersion in fresh-water; and 

 the Actinice may be stupified by adding fresh-water drop by drop until they lose the 

 power of retracting their tentacles. But the bivalves (such as Pholas) may be kept in 

 stale water till their valves full off with incipient decomposition, and yet the muscular 

 siphons retain their irritability, and contract slowly and completely, when placed lit 

 spirit. 



h3 



