ACADEMY OF SCIENCES. I i 



Female — Carapax as iu male. Chelipeds shorter than second pair, fingers 

 less widely gaping, no tooth on movable tinger. In other respects as in male. 



M. M. 



Length of carapax 21 



Width of ditto 18 



Length of first pair 24 



Length of second pair 29 



These dimensions are taken from the largest of eight specimens from Port 

 Escondido and San Jose Island, Gulf of California. 



Color, in spirits, bright red, the smooth manus, undersides of legs, and 

 buccal apparatus especially bright. 



No. 21. Male and female, in spirits. Fisher and Lockington. 



23. MithraculuA triangulatus. uov. sp. 



Carapax as broad as long; iu form an acute isosceles triangle truncated in 

 front ; regions prominent, antero-lateral margin with three lobes. Rostrum verj' 

 short, bifid, scarcely projecting beyond the line of the fixed joint of the outer 

 antennae, which terminates in a blunt tooth, followed by a second tooth or 

 rather lobe, forming part of the lower margin of the orbit. Outer antennae 

 ciliate, movable basal joints cylindrical, short; second joint considerably 

 stouter than the third. Lower margin of orbit formed by the teeth belonging 

 to the fixed antennal joint, followed by a small tooth intervening between 

 them and the laost-orbital. Pre-orbital tooth scarcelj^ evident, forming the ob- 

 tuse termination of the elevated orbital region. 



Chelipeds stout, longer than the second pair by almost the length of the 

 hand, arm tiibercular above, hand and carpus smooth, the former broad and 

 heavy, stoiater than the arm; dactyli obtuse and spoon-shaped at end, the 

 movable one with a single tubercle on the inner margin. 



Hinder limbs tubercular on upper surface; carapax and chelipeds without 

 tomentosity, but a few hairs scattered on the hinder limbs. Females much 

 smaller than males; the chelipeds small, about equal in length to the second 

 pair. 



Localitv— Gulf of California. 



M. M. M. M. 



Length of carapax 16 13.5 



Length of first pair 27 11 .5 



Length of second pair 15 12 



Width of carapax across the posterior portion, where widest. . . 14 12 



The areolets of the carapax are pi-ominent, but without spines; but the two 

 largest posterior lobes of the antero-lateral margin are tubercular, and there 

 are a few small tubercles on each postero-lateral margin. 



Color, iu spirits, uniform reddish. 



No. 15. Several specimens, both sexes, in spirits. Fisher and Lockington. 



24. Mithracidus coronahnt. Stimpson. Amer. Jour. Sci., second ser., 

 XXIX, 1860, p. 132; Am. Lye. Nat. Hist.. New York, VII, p. 186; White f?). 

 List. Crust. Brit. Mus., p. 7; T. Hale Streets, Proc. Acad. Nat. Sci., Phil., 

 Dec. 5, 1S71, p. 239. 



