136 BULLETIN 138^ UNITED STATES NATIONAL MUSEUM 



abdominal somites with longitudinal carinae. Raptorial dactylus 

 not inflated at base, armed with teeth on inner margin. Telson with 

 median carina, and smooth, pitted, tnberculate or carinate on either 

 side; distal margin Avith three pairs of large teeth; one or more sub- 

 median denticles, several (more than four) intermediate and one 

 lateral. 



Jurassic ; Cretaceous ; Eocene ; Miocene ; Pliocene ( ? ) ; Recent. 



CHLORIDELLA SONOMANA, new species 

 Plate 38. figs. 1 and 2 



Description. — This fragment is bent at its middle between the sec- 

 ond and third abdominal segments and the two halves pressed close 

 together. The fragment of carapace (c, fig. 2) shows 5 carinae, the 

 median carina is posteriorly bifurcated, the forks united a little in 

 front of the margin and then ending in an elongate tubercle. The 

 outer carina extends nearly to the posterior margin. The intermedi- 

 ate carina is interrupted by the transverse suture ; behind that point 

 it curves outward and then forward to unite with the outer margin. 

 The short fifth thoracic segment (-5, fig. 2) has no submedian carina, 

 and no lateral carina is in evidence. A lateral carina is present on 

 the sixth, seventh and eighth thoracic segments (6', ?', 5, fig. 2). The 

 carinae of the six abdominal segments are as follows : The submedian 

 carina is continuous, except on the first segment which has lost its 

 middle portion (i, fig. 2) ; the lateral carina is found on all, also the 

 submarginal carina except on the second segment (,^, fig. 2) where 

 its presence is indeterminable; marginal carina on first (fig. 2), 

 third and fourth (fig. 1) segments, second (fig. 2) and fifth (fig. 1) 

 indeterminable. None of the carinae now have terminal spinules but 

 the extremities show a place for their insertion; the only exception 

 among complete carinae is the submedian third abdominal which 

 diminishes gradually in height at its terminus. The lateral carina of 

 the sixth segment (fig. 1) is curved, concave outward, the anterior 

 half of the curve nearly transverse and situated near the anterior 

 margin; this half is followed by a shallow furrow across the ridge, 

 behind which there is a short, blunt, elevated, backward-pointing 

 tooth. Two median granules are present on second to fifth segments 

 inclusive, the sixth is broken in the middle. 



Measurements. — Holotype, length from anterior margin of fifth 

 thoracic segment to hind margin of sixth abdominal segment, about 

 72.3 mm.; wddth across fifth abdominal segment lacking lateral mar- 

 gins 32.7 mm. 



Occurrence. — California: 514 miles southeast of Santa Rosa, 

 three-tenths mile upstream from bridge crossing Matanzas Ctoek 



