150 H. C. STEVENS 



it by the observer. In the citations which follow, disguise is 

 the motive usually assigned to the animals. Thus in The Cam- 

 bridge Natural History, "Crustacea and Arachnids" 1 Smith 

 writes: 'The Spider crabs do not burrow, and their respira- 

 tory mechanism is simple ; but since they are forms that clamber 

 about among weeds, etc., upon the sea bottom, they often show 

 remarkable protective resemblances to their surroundings, 

 which are not found in the cyclometopa. * * * But besides 

 this, the long-legged forms such as Inachus, Hyas, etc., have 

 the habit of planting out Zoophytes, Sponges and Algae upon 

 their spiny carapaces, so that they literally become part and 

 parcel of the organic surroundings among which they live. It 

 may perhaps be wondered what are the enemies which these 

 armoured Crustacea fear." Similarly in the Riverside Natural 

 History 2 the writer, J. S. Kingsley, states " Some of these 

 forms keep their shells perfectly clean, seeming to rely upon 

 their general resemblance to the Sertularians and other hydro- 

 zoa, among which they dwell, for protection. Others, however, 

 permit all sorts of foreign bodies, both animal and plants, to 

 become attached to their bodies, so that they are effectually 

 concealed, and even when moving it seems as if a small forest 

 of sea-weed were being transplanted to another locality." In 

 the sentences just quoted the motive attributed to the animal 

 is again concealment, although the foreign bodies are said to 

 be permitted to become attached. Leunis 3 in discussing the 

 same group of animals says of them: "Die meisten haben 

 traege, langsame Bewegungen und tragen auf ihrer Oberflache 

 oft einen mehr oder weniger dichten Besatz von Prlanzen und 

 festsitzenden Thieren (Hydroidenpolypen, Schwamen, u. s. w.) 

 durch welchen sie leichterer vor den Nachstelligungen ihrer 

 Feinde verbergen konnen." 



It is evident from the quotations which have just been 

 cited, that the authors entertain different views as to the manner 

 in which the foreign bodies come to be upon the carapaces of the 

 crabs. According to one, the Zoophytes, etc., are "planted out ;" 

 according to another, the plant and animal forms are "per- 

 mitted" to become attached to the body of the crab. It soon 



1 Crustacea and Arachnids, p. 192. 



2 Vol. II, p. 61. 

 3 Zoologie, Bd. II, 649. 



