WEST AMERICAN CRUSTACEA. 579 



one-third as long as the preceding joints, the lower mar- 

 gins spinulous. Telson tapering to a truncated or broadly 

 rounded spinulous extremity. 



Length of specimen, 5 cm. 



Several specimens from Sonoma county, Cal. (L, E. 

 Ricksecker). 



Family PAL^MONID^. 



Pal^mon Ritteri sp. nov. 



Carapax shorter than one -half the length of the abdo- 

 men, the anterior half or third crested. There is a spine 

 beneath the angular suborbital projection of the anterior 

 margin of the carapax, and on the margin below this is 

 another situated behind the base of the second antenna 

 and above the rounded antero-inferior angle. No hepatic 

 spine. Rostrum a little longer than the carapax, and ta- 

 pering tolerably evenly from the widest portion (which is 

 about one -fourth as wide as the rostrum is long) to an 

 acute tip. The upper margin is armed with seven or 

 eight teeth of which the posterior one is situated on the 

 gastric region and the anterior one (often small) some 

 distance from the tip. On the inferior margin of the ros- 

 trum are three teeth, the anterior one rather remote from 

 the tip. Ocular peduncles short and stout; the ocellus 

 lies between the cornea and the stalk. The first basal 

 joint of the first antenna is about twice as long as broad; 

 the spine on the outer side reaching about to the middle 

 of the joint; there is a small tooth at the antero- external 

 angle. The next two joints are short and cylindrical; 

 the inner flagellum is slender and rather long. Outer 

 flagellum flattened and entire to a distance about equal to 

 the length of the third joint of the peduncle where it di- 

 vides into a slender, external portion which is longer than 

 the internal flagellum and a short and closely annulated 

 portion which is not greatly longer or shorter than the pe- 



