1911] MichaeJ: ChaetogiiaiJia of the San Diego Region. 47 



less opaque than the body, and the seminal vesicles do not 

 present such decided contrast as in S. serratodentata. The 

 form, with the comparatively large head and the body gradually 

 tapering from the head to a point at the tail, reminds one very 

 forcibly of a pin. The fins are barely visible as nearly trans- 

 parent areas. 



Characters 



Body firm and rigid, retaining its form well. Neck very pronounced 

 but made less conspicuous by the collarette which extends well toward, 

 but never reaches the ventral ganglion. Body nearly of uniform width, 

 but slightly wider from a point at a level with posterior end of anterior 

 fins to a point at a level with anterior end of posterior fins. This point 

 of greatest width varies from 52 to 60 per cent. Lateral fields small. 

 Muscles rather broad and strong. No constriction at tail-se])tuni. 



Anterior fin shorter and narrower than posterior fin. Extends to 

 posterior end of ventral ganglion. In form it is narrowly and acutely 

 triangular. 



Posterior /?« extends nearly, if not quite to seminal vesicles when 

 the latter are tumid. Ne\er more than 50 per cent of fin in front of 

 tail-septum. Widest slightly behind tail-septum. Half elliptical in 

 form. Interval from anterior fin to posterior fin considerably less than 

 the length of anterior fin. It varies from 8 to 16 per cent. 



Vestibular ridge (pi. 3, fig. 22) with very low and regular papillae. 

 Usually one papilla over each tooth. Wing of ridge covers all but one 

 tooth. Earely two teeth are exposed. External process very short, 

 barely including the first tooth. It is three or four times longer than 

 broad and about one-fourth the length of entire ridge. 



Anterior teeth 3 to 5, closely set, and not diverging much distally. 

 Posterior teeth 8 to 11, somewhat longer and proportionally narrower 

 than anterior teeth. Like anterior teeth, they do not diverge much 

 distally. 



Seizing jaivs (pi. 4, fig. 3-4) 7 to 9. Curvature about 53 per cent. 

 Point resembles, in form, that described by Krumbach (1903) for S. 

 hipunctata. It is, however, broader for its height and is inserted about 

 one-fifth instead of one-fourth of its height into the shaft. Top of 

 shaft and base of point parallel. Edge of point at intersection with 

 top of shaft, makes an acute angle with edge of shaft. Edge of point 

 and edge of shaft diverge proximad of this intersection. Bade of point 

 and back of shaft parallel. Pulp-canal central, with the pulp evenly 

 distributed. 



