CHAETAE 



267 



they consist of chitin, and each chaeta is the product of a 

 single cell. The chaetae of Euplirosyne are hollow and calcare- 

 ous, being peculiar in both characters. 



Fig. 138. Chaetae of various 

 Polychaetes (the magnifi- 

 cation is not the same in 

 all cases). A, Doubly- 

 fringed capillary, from 

 Terebellid ; B, hooded 

 crotchet, from Poly dor a ; 

 C, a fork, from Euphro- 

 syne ; D, jointed chaeta, 

 from Phyllodoce ; E, 

 simple chaeta, with ser- 

 rated ridges or frills, from 

 a Polynoid ; F, jointed 

 chaeta, from Eunice ; G, 

 uncinus, from Pomatoceros 

 (Serpulid) ; H, one of the 

 outer series of paleae from 

 the hood of Sabellaria 

 spinulosa ; I, jointed 

 chaeta, from a Syllid ; J. 

 multidenticulate crotchet, 

 from a Maldanid ; K, 

 comb-shaped chaeta, from 

 Eunice ; L, uncinus of a 

 Sabellid ; M, uncinus of 

 Terebel lid ( A mph itrite 

 Johnstoni) : a, edgewise ; 

 b, side view ; m, attach- 

 ments of muscles into ba, 

 basal plate ; x, accessory 

 teeth. N, Sheathed spear 

 of Hermione ; a, the spear- 

 shaped capillary removed 

 from its sheath ; b, the 

 same, with sheath. 



Certain modifications of the chaetae presented by various 

 worms deserve mention. In Poly dor a (Fig. 133, A) and in Chae- 

 topterus (Fig. 173, p. 324) those of one segment are especially 

 strong, but their significance is uncertain. In Capitella those 



