174 REPORT OF NEW JERSEY STATE MUSEUM. 



According" to S. I. Smith the tubes of all the specimens seen 

 are black externally, thin, very regularly cylindrical, except that 

 they are usually slightly enlarged at one or at both ends. Within 

 they are smoothly lined with a layer of cement, while externally 

 they are covered, to a g"reat extent at least, with minute elongated 

 pellets, apparently the excrement of the animal, arranged trans- 

 versely to the tube and closely crowded together. There appear, 

 however, to be other materials, probably minute fragments of 

 alg^e, hydroids, etc., mixed with the pellets. The tube is appar- 

 ently never attached, but is carried about by the animal, xevy 

 much after the manner of the larvae of some species of Phry- 

 ganeidas, as descriljed by Say. It is very difficult to force the 

 living animal from its tube, and it probably never quits the tube 

 voluntarily. The ordinary position of the animal when at rest 

 is with the head only protruding from one end of the tube, the 

 antennultC stretched out in front and diverging at about a. right 

 angle while the antenucne are held out each side at right angles 

 to the tube. The antennulre and antennas are the only appendages 

 which are ordinarily used in locomotion, and by means of these 

 alone the animal appears to mo\e about with its tube with the 

 same ease and rapidity as the species of Podocerus and 

 Corophium do ^^•hen unencumbered. As noticed by Say, the 

 animal turns about within its tube very readily, and uses either 

 end of it indifferentl}' as the front. If the tube catch in any 

 w^ay while the animal is moving about or if it be held fast by 

 forceps, the head is protruded first from one and then the other 

 end of the tul>e in quick succession, and the antennuLT and 

 antennae are thrust along the outside of the tube to discover the 

 obstruction. While thus held fast, fully half the body is often 

 protruded from the tube. In turning about within the tube, the 

 terminal segments of the pleon are thrust forward beneath the 

 anterior segments and the perason pulled back over them, and 

 then the peraeon is folded back upon itself in the same way, 

 but the antennulae, antennae and head are never first bent beneath 

 the peraeon. The structure of the telson, second and third 

 uropods, and of a part of the perseopods is well adapted to the 

 performing of this evolution. The hooks of the second and third 

 uropods and of the telson holding the tail fast to the side of 



