1911] Michael: Chaetognailia of the San Diego Region. 29 



usually about 10 per cent, but varies from 9 to 15 per cent. Interval 

 always less than length of posterior fin. 



Vestibular ridge (pi. 3, fig. 14) provided with low rounded papillae 

 having the appearance of a number of irregular semicircles. Number 

 of papillae usually the same as number of posterior teeth. Two teeth 

 (sometimes one) project beyond wing of ridge, the third (or second) 

 barely reaching the wing. Notch covers the first three or four teeth. 

 External process from one-half to one-third the length of ridge. It is 

 blunt and narrow, its length being about ten times its width. 



Anterior teeth, 5 to 8. Posterior teeth, 8 to 12, somewhat higher and 

 broader than corresponding anterior teeth. 



Seizing jaws (pi. 4. fig. 26), 8 to 9 in number. Curvature of jaw about 

 55 per cent. Point with an oval base and imbedded from 24 to 27 per 

 cent of its height into shaft. Near its base the edge of point is notched. 

 Base of point and top of shaft converge in approaching edge of jaw. 

 Pulp-canal displaced slightly toward back of jaw. Pulp evenly distrib- 

 uted throughout canal. 



Corona ciliata (pi. 7, fig. 45), short and almost entirely on head. It 

 was characteristically absent in most of the San Diego material. Accord- 

 ing to Fowler (1906) it varies from a "simple sinuous outline to a 

 complex hour glass shape." The same variation has also been noted by 

 Ritter-Zahony (1909b). 



TABLE 1 



Measurements of Sagitta enflata^ 



1 All measurements made in per cent of total length of animal. 

 - Per cent of posterior fin in front of tail-septum. 



