30 University of California Puhlicatioits i)i Zoology. [Vol.8 



The table above shows more accurately the measurable taxonomie 

 features of this species. In nos. 1 and 2 the width appears as 12 per cent, 

 but is probably incorrect owing to pressure of the cover glass. Also in 

 no. 2 the posterior fin was so torn that the width appears too small. 

 Again no. 5 was wrinkled so as to make the width appear too small. 



In comparing this table with that of Fowler (1906) we 

 notice several interesting differences. The number of anterior 

 teeth averages less than he has obtained, the variation he found 

 being from 6 to 10, while the San Diego material varies only 

 from 4 to 8. The usual number he found to be 8, while we 

 have found but one instance of 8, the usual number being 7. 

 We never found an individual with more than 8, while Fowler 

 (1906) records some twenty per cent having 10. Again, in 

 the number of posterior teeth. Fowler (1906) finds a variation 

 often to 17, while the San Diego specimens vary only from 6 to 

 12, the usual number being 10 or 11. Rarely the number drops 

 as low as 5. 



Sagitta enfiata, at first sight, very strikingly resembles »9. 

 pulchra, S. hexaptcra, and 8. lyra. This is especially true if the 

 specimens are not well preserved. It is, however, readily separ- 

 able from 8. Ju.raptera by the tooth-formula, and especially the 

 structure of the vestil)ular ridge. It differs from S. lyra by not 

 having confluent anterior and posterior fins, and from S. pulchra 

 by absence of the collarette. 



Sagitta hexaptera d'Orbigny 



PI. 1, fig. 2; pi. 3, fig. 15; pi. 4, figs. 27, 28; pi. 6, fig. 44. 



Sagitta hexaptera d'Orbigny (1843), p. 140; Darwin (1844), p. 2; 



Hertwig (1880), p. 196; Grass! (1883), p. 10; Krumbach (1903), 



pp. 633, 634; Fowler (1906), p. 11; Ritter-Zahony (1908), p. 9, 



(1909b), p. 8. 

 Sagitta hiimnetata, Krohn (1884), p. 108; Gegenbaur (1856), p. 14; 



Langerhans (1880), p. 135. 

 Sagitta tricuspidata Kent (1870), p. 268. 



Sagitta magna Langerhans (1880), p. 135; Grassi (1883), p. 11. 

 Sagitta darwini Grassi (1883), p. 19. 



General Appearance 



This species may be recognized as one of the largest of the 

 Chaetognatha, sometimes reaching a length of 70 mm. When 

 placed upon a black background 8. hexaptera presents a very 



