40 University of California Publications i)i Zoology. [Vol. 8 



row of teeth and provided with low, rounded papillae, each one approxi- 

 mately representing the quadrant of a circle. They are fewer in number 

 than posterior teeth. Three or four teeth project beyond wing of ridge, 

 the notch extending to the sixth or seventh tooth. External process 

 one-fourth to one-fifth the length of entire ridge. It is from two to 

 three times broader at end than at wing. 



Anterior teeth, 6 to 9 in number. They are conical, closely set, and 

 slightly diverging distally. Posterior teeth, 13 to 19 in number. Similar 

 in form to anterior teeth, but apparently shorter and broader. They 

 are very closely set. 



Seizing jaws (pi. 4, fig. 30), according to Fowler (1905), vary from 

 6 to 8 in number. In the San Diego specimens the number varies from 

 5 to 7. Curvature about 54 per cent. Shaft usually conspicuously ser- 

 rated, the serrations, gradually and somewhat irregularly, increasing 

 in size proximally, and disappearing entirely somewhat above middle of 

 jaw. Point curved toward edge of jaw presenting the variation that 

 Krumbach (1903) demonstrated. Point imbedded about 25 per cent of 

 its height into shaft. Top of shaft and base of point parallel. Pulp 

 evenly distributed throughout canal, the latter being slightly displaced 

 toward back of jaw. 



TABLE 7 

 Measurements of Sagitta serratodentata^ 



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



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



The action of formalin causes the lateral fields to shrink inward, 

 with the result that the fins are nearly hidden from view. As a con- 

 sequence, width-measurements of the fins could not be made with any 

 accuracy except in the first two specimens, which were measured directly 

 after preservation. In no. 1 width of anterior fin was 3.5 per cent, pos- 

 terior fin 6.2 per cent. In no. 2 the widths were 3.0 and 6.0 per cent. 



