190 HISTORY OF BRITISH CRUSTACEA. 



Some, if not the majority, of the species of the group 

 named Podoceridce by Leach, inhabit a tube considerably 

 resembling that of the Caddis-worms (JP7iryganeida). Mr. 

 Say has described* one of these, a native of the sea-coast 

 of the United States. The Cerapus tubularis, as he calls it, 

 is about a quarter of an inch long, and is found amongst 

 seaweeds on the beach of Egg-harbour. It is a very active 

 little animal, running with great ease amongst the algre 

 and corallines, notwithstanding the encumbrance of its cy- 

 lindrical tube. The true feet are included in the tube, ex- 

 cepting the two front pairs, with which it seizes its prey and 

 conveys the captures to its mouth. The four elongated an- 

 tennae, which are more than half the length of the creature, 

 are employed as walking feet. When the Cerapus swims 

 about, the half of the body is projected from the tube, and 

 is suddenly and often bent, so that it advances by a series 

 of jerks. The tube, Say thinks, is not constructed by the 

 Cerapus, who chooses, much after the fashion of the Hermit 

 Crab, the residence, abandoned or tenanted, of a Tubularia, 

 one of the Annelids very common on the coast. This abode 

 is always in proportion to the size of the animal ; although 



* Joum. Acad. Nat. Sciences, of Philadelphia, vol. i. pp. 49-52, pi. iv. 

 fie. 6, 7-11. 



