42 NATURAL SCIENCE. July, 1896. 



explanation of their use. They can be regarded as waste products 

 which in this way are most conveniently eliminated from the body. 

 In opposition to a commonly received view, that they assist in 

 supplying lime for the formation or hardening of the new shell, it is 

 pointed out that the proportion they bear to the whole exoskeleton is 

 so trifling that they cannot be of any practical service in providing 

 calcareous matter for it. None the less, the position of the gastro- 

 liths is so peculiar that they are not easily thought of as mere 

 offscourings. One lies on each side of the stomach in a pocket 

 formed between the old cuticle which is about to be shed and the 

 new one which is to take its place. Had they no purpose to serve 

 but that of throwing off superfluous matter, one would expect them to 

 be cast out along with the old lining of the stomach. But this is not 

 the case, and it may therefore be conjectured that in the first instance 

 they give support to the weak and soft new lining, and that, when 

 presently their prismatic structure breaks up and falls into the cavity 

 of the stomach, they then help to fill for a time what would otherwise 

 be an aching void. The ' soft lobster,' after the exertion of shedding 

 its tunic, may soon begin to feel hungry, and yet the feeding upon 

 miscellaneous prey would not be without its serious perils when the 

 stomach is just recovering from the delicate task of exuviation. 



Without going into further details, it may be said in conclusion 

 that, after a complete study of Dr. Herrick's volume, the reader will 

 probably be disposed to regard its writer as " the latest and best 

 authority " on the American Lobster. 



Thomas R. R. Stebbing. 



