536 THE ZOOLOGIST. 



Othonia gracilis, and crusting colonies of Bryozoa protruding 

 ever and anon circlets of hair-like tentacles." Hence, when the 

 hairy H. fascigera is at rest on such a weed, the mimetic adaptation 

 is greatly accentuated.* Thus also the connection of the small 

 Short-tailed Crab (Nautilograpsus minutus), which swarms on the 

 Gulf-weed, and assimilates in colour thereto. Sir John Murray, 

 during the voyage of the * Challenger,' studied the habits of these 

 Crabs. He observed " that, although every floating thing upon 

 the surface is covered with them, they are rarely met with swim- 

 ming free, and that whenever they are dislodged and removed a 

 little way from th<ir resting place they immediately make the 

 most vigorous efforts to regain it.''f The Common Shrimp 

 (Crangon vulgaris), when suspecting danger, " sinks upon the 

 sand, and, setting his swimming-feet rapidly to work, they 'kick 

 up such a dust ' in the water that he is hidden in a cloud of fine 

 sand, which as quickly settles down and partially buries him — 

 sufficiently so with his sandy hue to effectually hide him." J Mr. 

 W. A. Lloyd has described a somewhat similar habit of the Echinus 

 or Sea-urchin. " Its chief delight, when in an aquarium, appears 

 to be to cover itself with pebbles, which it picks up with its spines. 

 At first I imagined that the little stones had fallen by mistake, 

 and, wishing to do all in my power to render my captive happy, I 

 removed the pebbles with a brush ; but the Sea-urchin evidently 

 did not appreciate my would-be kindness, for in a short space of 

 time he had again covered himself with pebbles ; and so com- 

 pletely was he hidden beneath them, that if he had not crawled 

 up the side of the aquarium with his load I should have had 

 some difficulty in discovering his whereabouts. "§ Some species 

 of Crabs, such as Maja verrucosa, Pisa tetradon and P. armata, 

 Inachus scorpioides, and Stenorrhynchus longirostris, cut off bits 

 of Wracks, Floridece y Ulvce, &c, with their claws, and place them 

 on the top of their carapaces, securing them on peculiar spiky or 

 hooked hairs. The fragments grow firmly to the Crabs' chitinous 

 coats, and, far from being harmful to the animals, are, on the 



* ' The Journal of Marine Zoology and Microscopy,' vol. ii. pp. 101-103. 

 f Cf. Sir C. Wyville Thomson, 'The Voy. of the Challenger.' — " The 

 Atlantic," vol. ii. p. 11. 



t Edw. Step, 'By the Deep Sea,' p. 168. 

 § ' Life beneath the Waves,' pp. 83-4. 



