190 
HISTORY OP 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 ( Phryganeida ?). Mr. 
Say has described * one of these, a native of the sea-coast 
of the United States. The Cerhpus tub u laris, 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 algm 
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 Tubular ia, 
one of the Annelids very common on the coast. This abode 
is always in proportion to the size of the animal ; although 
* Journ. Acad. Nat. Sciences, of Philadelphia, vol. i. pp. 49-52, pi. iv. 
fig. 6, 7-11. 
