TUBE DWELLINGS. 193 



TUBE DWELLINGS, 



AND THEIR BUILDERS. 



The caterpillars of tlie caddice flies build them- 

 selves little portable dwellings of sticks, grass stems, 

 small shells, and such matters, which they drag about 

 after them over the bottom of the pond or stream in 

 which they live, as hermit crabs do the shells they in- 

 habit beneath the surface of the ocean. 



Some of the tubes of the caddice worms, however, 

 are fixed, in which case they resemble not so much 

 the hermit crab as the so-called marine worms. 



These marine worms, though called by that name, 

 do not in the least resemble anything we commonly 

 know as worms, the emblems of abasement and help- 

 lessness ; on the contrary, they hold themselves erect 

 in the handsomely constructed tubes they build, and 

 sit like kings upon their thrones, wearing magnifi- 

 cent crowns of gemhke brilKancy and splendid color. 

 These crowns are their gills or breathing apparatus, 

 and also serve to convey food to their mouths. Each 

 of the rays that form the crown or gill tuft consists of 

 a translucent stem, from which springs a double row 

 of secondary rays like the teeth of a comb. 



When looked at with a magnifying glass, the red 

 blood may be seen coursing along the artery and back 

 again by the veins with ceaseless motion, forming a 

 very strikiug spectacle. The rays or filaments are 



