ADDENDUM TO CHAETOGNATHA 



Since the Chapter on the Chaetognatha was printed the 

 following list 1 of " The Known Chaetognaths of American 

 Waters " has appeared : 



1. Sagitta elegans Verr. This species resembles S. bipunctata (vide pp. 



191 and 193), but differs in size, in the relative proportions of 

 caudal and body segments, and in the presence of diverticula from 

 the intestine. 



2. Sagitta, flaccida Con. This species resembles S. hexaptera (vide p. 193) ; 



it is, however, smaller (length, 1-3-1-8 cm.) and has more spines 

 (anterior, 7-8, posterior, 10-12), and its tail segment is relatively- 

 smaller. 



3. Sagitta tenuis Con. Length, 5-25 mm. ; hooks, 7-8 ; anterior spines, 



4-5 ; posterior spines, 7-10. 



4. Sagitta hispida 2 Con. Length, 7-11 mm.; hooks, 8-9; anterior spines, 



4-5; posterior spines, 8-15; tail segment one-third body length; 

 intestine with two diverticula ; sensory hairs very numerous. 



5. Sagitta hexaptera (vide p. 193). 



6. Krohnia hamata (vide p. 194). 



7. Spadella maxima Con. Length, 5*2 cm.; hooks, 6; anterior spines, 3-5; 



posterior spines, 5-7 ; epidermal thickenings round the neck. 



8. Spadella draco (vide p. 194). 



9. Spadella schizoptera 2 Con. An ojoaque, yellowish -brown species living 



among algae. Length, 4 mm. ; hooks, 8 ; anterior spines, 4-6 ; 

 posterior spines wanting. Caudal segment occupies one-half the 

 body length. 



Professor Verrill states that the name S. gracilis (vide p. 191) 

 was due to a clerical error, the species really referred to being 

 JS. elegans. A. E. S. 



1 F. S. Conant, Johns Hopkins Univ. Circ. vol. xv. 1896, p. 82. 

 2 Ibid. vol. xiv. 1896, p. 77. 



