THE FOSSIL STALK-EYED CRUSTACEA 47 



it bears a larger, backward-pointinfi:, basal lobe, and several smallish 

 lobes. The upper half of the minor palm appears of similar shape 

 to the major one, its superior length is about four-sevenths that of 

 the major palm. 



Only the impressions of the merus of the first and second legs 

 of the right side are visible; they are long and narrow, the second 

 one reaching to the lateral spine of the carapace. 



The sternum is nearly fiat, the male abdomen small, with all seven 

 segments distinct, the third segment reaching apparently across the 

 sternum to the coxae of the hind legs (pi. 11, fig. 1). 



MeasureTiients. — Length of carapace, in median line, of male holo- 

 t3^pe 32 mm. ; width at sinus immediately in front of spine or tooth 

 at lateral angle, this spine being incomplete on both sides of the 

 carapace, 42.5 mm. : height of right or major manus near distal end 

 20.2 mm. 



Occurrence. — California; Rock Creek quadrangle; Martinez for- 

 mation (the lowest Eocene formation of California) ; one male speci- 

 men, showing the greater part of the body and chelipeds; holotype, 

 Cat. No. 353370, U.S.N.M. 



Relation. — This species resembles most the type species of the 

 genus, G . vigil A. Milne Edwards,^* from the Eocene of northern 

 Italy. Our species differs in its narrower orbits and consequently 

 more oblique antero-lateral margin, in the shorter postero-lateral 

 margin (which in G . vigil is about twice as long as the antero-lateral 

 margin) ; in the greater inequality of the chelipeds of the male;^^ 

 and in the narrower abdomen of the male. 



Family XANTHIDAE Alcock 



Carapace more or less transversely oval; front moderately broad^ 

 often toothed, in the latter case always with a median notch ; antero- 

 lateral margins arcuate, armed with several lobes, teeth or spines. 

 Antennules fold back transversely or obliquely. Fingers of cheli- 

 peds more or less curved. 



Genus ZANTHOPSIS M'Coy 



Zanthopsis M'Coy, Ann. Mag. Nat. Hist., ser. 2, vol. 4, 1849, p. 162; type, 

 Z. leachii (Desmarest). 



Carapace very convex, oval, furnished with a definite number of 

 large tubercles or bosses. A few tubercles or lobes on antero-lateral 

 margin. Front quadrilobate. Chelipeds massive, fingers pointed. 

 Third, fourth, and fifth segments of male abdomen fused. 



Cretaceous; Oligocene. 



"Ann. Sci. Nat., ser. 5. Zool.. vol. 3. 186.5, p. 324, pi. 12, figs. 1-3. 



'5 See Bittner, Denksch. k. Akad. Wiss., math.-naturw. CI., vol. 34, Abth. 2, Wien, 1875, 

 pi. 5, figs. 1 and 3. 



