46 A Guide to the Zoological Collections in the 



swimming Polychxta^ and the Tuhicola or sedentary Poly- 

 chseta. 



POLYCH/ETA ERRANTfA. 



The Errantia, or free-swimmers, live usually in sand and 

 mud and shallow water near the coast: some, however, in- 

 habit the abyssal depths, and some live habitually at the 

 surface of the ocean. In accordance with their manner 

 of life they have a distinct head with powerful biting jaws 

 (well seen in Eunice), and have well-developed parapodia 

 and setae for locomotion, and usually large and numerous 

 branchiae or breathing organs. Although freely locomo- 

 tive they sometimes inhabit thin tubes, as may be seen in 

 Hyalincecia. 



POLYCH/ETA TUBICOLA. 



The Tuhicola or sedentary Sea-worms live in protective 

 tubes or shells, which they either manufacture, or actually 

 secrete for themselves. The tubes may consist of grains 

 of Pand and stones and broken shells glued together by a 

 sticky secretion, or of chitin strengthened with sand, etc., 

 or of carbonate of lime. Examples of these different tubes 

 are exhibited in Case 43. 



Being sedentary, the Tuhicola have no need of para- 

 podia and setae for locomotion, and these structures there- 

 fore along with branchiae are quite rudimentary. The 

 head is indistinctly demarcated from the rest of the body, 

 and there are no jaws. On the other hand the anterior 

 end of the body, which can be protruded from the tube, is 

 provided with bundles of long thread-like tentacles which 

 are not only used for sweeping food into the mouth, but 

 are also organs of respiration. 



These tentacles are beautifully shown in the exhibited 

 specimens of Cirratulus filigerus and Spirographis 

 spallanzani from the Gulf of Naples. 



In the exhibited collection the Polychaeta are repre- 

 sented by specimens of the following genera from Indian 

 seas : — 



Errantia — Chloeia, Eurythoc^ Aphrodita, Eupompe, 



