1885. J HiihUs of Cyrtopliiiiiu cMlaiiiicola. 67 



anterior tlio largcsi), tlie 3rd the smallest ; 4th with the rami unequal, 

 the internal ramus two- jointed, projecting backwards and inwards behind 

 the telson like a pair of horns ; 6th smaller than the fourth, with in . 

 ternal ramus rudimentary ; 6th rudimentary, bud-shaped, with a few 

 very short, straight, backwardly directed, appressed sj^ines. Telson 

 short, blunt, conical, and armed, at the extremity of the dorsal surface, 

 with spines similar to those on the last abdominal appendages. 



The tuhe inhabited by this little creature is a very curious struc- 

 ture. It is, as a rule, considerably longer than the body of the animal 

 it shelters, being more than capable of completely protecting it, when 

 the antennae, extended in front of the body, are drawn within. It 

 is of a deep golden brown colour, and, on closer examination, is seen 

 to be closely, but irregularly, banded with zones of darker and lighter 

 tint, varying from a fine golden yellow, through a warm brown, to 

 black. When some of this material is teazed out, it is seen to consist 

 of coarse, nearly opaque, fibres uniformly stained throughout, and show- 

 ing no structure, consisting, indeed, to all appearance, of a hardened 

 secretion. For some time I was in considerable doubt as to the method 

 of its manufacture. At first I had jumped to the conclusion that it was a 

 worm tube that had been appropriated by the Cyrtopliiwtn, much in the 

 same way that a hermit-crab fits itself with the shell of a dead mollusc. 

 One day, however, I surprised one of the amphipods, in my live trough, 

 evidently in the act of repairing its premises. The animal had completely 

 withdrawn himself into the tube and was keeping it slowly but continu- 

 ously revolving round him. The specimen was luckily a small one and 

 hence the tube was transparent enough for me to see that the crustacean 

 kept stationary, while the tube revolved. The transparency, however, was 

 not sufficient to enable the exact method of deposition of the fibre to be 

 made out. Shortly after this, a specimen was met with in which about 

 half the tube only was covered with the opaque fibrous material and the 

 other half transparent. On placing this beneath the microscope, I was 

 surprised to find that the transparent portion was a very complex, 

 structure consisting of a layer of hexagonal thick-walled cells with 

 an outer layer of long quadrilateral cells ; the whole presenting an 

 appearance which left one in no doubt as to its vegetable nature. 

 Moreover, the structure was not that of an alga, and appeared most 

 probably referable to that of some grass or reed. The greater part of 

 this vegetable membrane was coated on both sides with the peculiar 

 opaque fibrous material above described . Pieces of grass such as would 

 serve for this purpose are taken commonly enough in the surface-net 

 in the turbid waters at a river's mouth and are, no doubt, common 

 at the bottom for some considerable distance beyond ; indeed , I 

 8 



