Clearing up a Mystery. 191 



It was read on November 29, 1859. It showed the 

 improbability of an epidemic attacking four different 

 species at once, established the fact that the usual 

 food for these particular birds had been wanting from 

 exceptional causes, and that specimens of the birds 

 which had been examined exhibited no traces of 

 organic disease, but that both the conduct of those 

 which survived and the condition of those which 

 perished negatived the hypothesis of an epidemic, and 

 pointed clearly to the effects of starvation. 



When this paper was read, "the chairman took 

 the opportunity of saying that Mr. Robertson's in- 

 genious and apparently satisfactory explanation might 

 be looked upon as a final contribution towards the 

 elucidation of the mystery which had lately attracted 

 so much attention." 



As this is not intended for an encyclopaedia of 

 marine zoology, it will not be possible here to give 

 anything like a full and clear account of those results of 

 his extremely active researches which Mr. Robertson 

 from time to time laid before the society. 



At one time we find him discussing the principles 

 of architecture on which the tube of an annelid is 

 constructed, at another explaining the advantage a 

 hermit crab derives from having its claws unsym- 

 metrical, one of them being very small for quickly 

 plying its mouth with food, the other very large 

 for holding its prey and supplying an organic door to 

 its castle. Among various other starfishes, rare or 

 abnormal, he exhibited a specimen of the common 

 five-fingers, U raster rubens* which " showed a curious 



* Asterias rubens^ Linn. 



