42 University of California Puhlications in Zoology. [Vol.8 



Posterior fin longer and broader than anterior fin, extending to seminal 

 vesicles when latter are tumid. Always more than 50 per cent of fin in 

 front of tail-septum. Interval from anterior to posterior fin varies from 

 4 to 11 per cent, but is usually 6 or 7 per cent, and is never over half 

 the length of posterior fin. 



Vestibular ridge (pi. 3, fig. IS) provided with low, blunt papillae con- 

 siderably irregular in form. Usually one papilla for every posterior 

 tooth. Ridge covers all except the last one or two teeth. External pro- 

 cess acute, narrow, and long, being about half as long as the rest of 

 the ridge. Certain individuals present the appearance (pi. 3, fig. 19) 

 of a double ridge similar to that noted by Fowler (1905) in S. decipiens, 

 both parts possessing acute external processes which fork apart at the 

 point where the wing of the ridge descends. 



Anterior teeth, 5 to 8 in number. They are closely set and conical 

 in form. Posterior teeth 9 to 14, and similar, in form, to anterior teeth. 

 They are, however, larger excepting the first and last, which may be 

 slightly shorter. 



TABLE 8 



Measurements of Sagitta bipunctata^ 



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



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



Though obtained by the thousand, the head in nearly every case was 

 extremely contracted, thereby making a correct count of the teeth almost 

 impossible. 



