526 THE ZOOLOGIST. 



EDITORIAL GLEANINGS. 



Dr. A. Alcock, the Superintendent of the Indian Museum, Calcutta, 

 has just published, in the * Journ. Asiat. Soc. Bengal,' a very interesting 

 account of a new Hermit-Crab (Chlanopagurus andersoni) exhibiting adaptive 

 commensalism with a Sea- Anemone.* The Hermit-Grab is noteworthy (1) 

 in having for its refuge, not the usual mollusc-shell, but a sheet or blanket 

 formed by the ccenosarc of a colony of Sea-Anemones ; (2) in being — as far 

 as the male is concerned — symmetrical ; aud (3) in having the appendages 

 of the 3rd-5th somites of the male, and of the 2nd-5th segments of the 

 female, present on the right or left side indifferently. 



" There is nothing unusual in the fact that the protective covering of 

 the abdomen is not a moliusc-shell, for in these seasf alone there are 

 several well-known instances of Hermit- Crabs making use of other convenient 

 receptacles. For instance, Pylocheles miersi is found impacted in hollow 

 twigs of sunken drift-wood ; Troglopagurus, according to Messrs. Thurston 

 and Henderson, lives in small cavities in coral; and I have myself seen a 

 large Ccenobita, on the island of Minnikoy, holding the empty shell of a 

 small coco-nut over its abdomen. Again, in other parts of the world, 

 Gryllopagurus lives in burrows of its own construction ; Pylocheles Agassizii 

 was found concealed in a cavity in a piece of sandstone, and another specimen 

 was taken from the gastral chamber of a siliceous sponge ; Xylopagurus rectus, 

 like our Pylocheles miersi, was discovered in a lodging in drift-wood ; Os- 

 traconotus and Tylaspis are both believed to have some special protective 

 shield, other than a shell ; and Porcellanopagurus lives free among sea- 

 weed. 



"Again, the association of our new form of Hermit-Crab with a Sea. 

 Anemone is nothing strange : indeed, commensalism between Crustacea 

 aud Sea-Anemones is one of the most familiar facts of zoology, and a large 

 number of instances of it have been described. In most cases, however, 

 the facts seem to be that an individual of a definite species of Crab and an 

 individual of a definite species of Sea-Anemone have both at once taken 

 possession of the same mollusc-shell, which they continue to inhabit for 

 their mutual advantage, — the Crab acting as locomotive to the Sea-Anemone, 



* Belonging to the family Zoanthidce, but apparently not referable to 

 any known genus. 



f The species was dredged by the ' Investigator' off Cape Comorin. 



