THE CADDIS SHRIMP — THE BEAVER. 431 



These are the habitations of a very small crustacean {Cerapus 

 tuhdaris), properly called the Caddis Shrimp, because the tube 

 which the creature makes is analogous to that which is formed 

 by the caddis larvae. The animal which inhabits this case is a 

 curious little being, very like the long-bodied, long-legged ca- 

 prellse, that are so plentiful among sea-weeds, and furnished with 

 two pairs of long and stout antennas, and two pairs of grasping 

 feet. As the tube is too short to contain the entire animal, the 

 long antennae are always protruded, and occasionally the powerful 

 grasping feet are also thrust out of the opening. 



The antennae are continually flung forward and retracted in a 

 manner that reminds the observer of the movements of the acorn 

 barnacle, each grasp being evidently made for the purpose of 

 arresting any passing substance that may serve for food. This 

 remarkable little crustacean is generally found upon the well- 

 known alga which produce the Carrageen, or Irish Moss (Ghxmdrus 

 crispus). It will not, however, be found upon those plants which 

 can be plucked by hand, but resides in deeper water, so that the 

 best method of procuring it is to go out in a boat, throw the drag 

 overboard, and then examine the algse which are torn from their 

 attachments. 



CHAPTEE XXI. 

 social habitations. 



SOCIAJ/ SIASIMALIA. 



The Beateb. — Its Form and aquatic Habits. — Need for Water, and Means used to 

 procure it. — Quadrupedal Engineering. — The Dam of the Beaver. — Erroneous 

 ideas of the Dam. — How the Beaver cuts Timber. — The Beaver in the Zoological 

 Gardens. — Theories respecting the Beaver's Dam, — How the Timber is fastened 

 together. — ^Form of the Dam, and mode of its Enlargement. — Beaver-dams aiid 

 Coral-reefs. — The House or Lodge of the Beaver. — Its Locality and Structure. — 

 Use of a subterranean Passage. — How Beavers are Hunted. — Curious Supersti- 



, tion. — "Les Paresseux." 



We now come to the Social Habitations, and give prece- 

 dence to those which are constructed by Mammalia. 



Of the Social Mammalia, the Beaver ( Gaster fiber) takes the 

 first rank, and is the best possible type of that group. There are 

 other social animals, such as the various marmots and others; 

 but these creatures live independently of each other, and are only 

 drawn together by the attraction of some favorable locality. The 



