Cerainis, Unciola., and Lepidactylis. 2Y5 



crowded toi^etlier ; tlierc appi'iir, however, lo be other niateriuls, 

 prol):il)ly iiiiiiute fragments of algai, Iiydi'oids, etc., mixed with the 

 pellets. The tube is apparently never attached, but is carried about 

 by the animal, very much after the manner of the larvte of some 

 species of Phryganeida3, as described 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 anten- 

 nula3 stretched out in front and diverging at about a right angle, 

 while the antenmnp are held out each side at right angles to the tube. 

 The antennuhe and antennae are the only appendages which are ordi- 

 narily used in locomotion, and by means of these alone the animal 

 appears to move about with its tube with the same ease and rapidity 

 as the species of Podocerus and Corophiuni do when unencumbered. 

 As noticed by Say, the animal turns about within its tube very 

 readily, and uses either end of it indifferently as the front. If the tube 

 catch in any way while the animal is moving about, or if it be 

 held fast by forceps, the head is protruded first from one and then 

 from the other end of the tube in quick succession, and the antennulae 

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



branches of the alga, though occasionally a branch of the alga was bitten off and 

 added to the frame-work ; but very soon the animal began to worlc bits of excrement 

 and bits of alga into the net. In this case the pellets of excrement, as passed, were 

 takfcn in the giiathopods and maxillipeds, and apparently also by the maxillae and 

 mandibles, and broken into minute fragments and worked through the web, upon the 

 outside of which they seemed to adhere partially by the viscosity of the cement 

 threads and partially by the tangle of threads over them. Excrement and bits of 

 alga were thus worked into the wall of the tube until the whole animal was protected 

 from view, while, during the whole process, the spinning of cement over the inside of 

 the tube was kept up. When spinning the cement threads within the tube, the animal 

 was held in place on the ventral side by the second pair of gnathopods and the caudal 

 appendages, the latter being curved beneath the anterior portion of the pleon, and on 

 the dorsal side by the third, fourth and fifth pairs of perasopods extended and turned 

 up over the back, with the dactyli turned outward into the web. The spinning was 

 done wholly with the first and second perseopods, the tips of which were touched from 

 point to point over the inside of the skeleton tube in a way that recalled strongly the 

 movements of the hands in playing upon a piano. The cement adhei'ed at once at the 

 points touched and spun out between them in uniform delicate threads. The threads 

 seemed to harden very quickly after they were spun and did not seem, even from the 

 first, to adhere to the animal itself. In one case in which the entire construction of 

 the tube was watched, the work was apparently very nearly or quite completed in 

 little more than half an hour. In a species of Amphithoe, in which the construction 

 of the tube was watched, the process was very similar, though less cement and more 

 foreign material seemed to enter into the structure. 



Trans. Conn. Acad., Vol. IV. 36 July, 1880. 



