CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION II 



6. MICROPISA OVATA Stimpson 



Pirate I, Fig. 3, T,a 



Micropisa uvata Stimpson, Proc. Acad. Nat. Sci. Phila., ix, p. 217 [24], 



1B57. 



In this little crab the carapax is rather depressed, and but little 

 longer than broad. The regions are sufficiently prominent, but gen- 

 erally smooth and rounded ; there are, however, three inconspicuous 

 protuberances on the genital and three on each branchial region. 

 Surface pubescent, the more prominent portions often surmounted 

 by a few curled sets. The antero-lateral margin is swollen, but with- 

 out teeth, except that immediately behind the post-orbital tooth and 

 a small conical one at the lateral extremity of the branchial region. 

 The chelopoda of the adult male are robust ; the meros toothed along 

 the angles ; the hand smooth, somewhat compressed, and surmounted 

 above by a ridge. Posterior four pairs of feet pubescent ; the meros 

 with a small tooth at the summit and one or two near the base. 

 Length of carapax. 0.4 ; width, 0.38 inch. 



Several specimens were taken in the harbor of Porto Praya, Cape 

 de Verde Islands. They were dredged on a nuUipore bottom at the 

 depth of 20 fathoms. 



Genus TIARIXIA Dana 



In addition to the characters given by Dana as defining this well- 

 marked group, the following may be added. The palpus of the ex- 

 ternal maxillipeds i^ very broad : but little less than three-fourths as 

 broad as the ischium or second joint; the antero-exterior angle of 

 the meros is consequently much produced. As in many other genera 

 of Alaioids. the fingers of the chelopoda are in contact throughout 

 their length in llie young, but touch each other only at their tips in 

 the adult ; the dactylus bears a strong tooth within near its base. In 

 Tiariiiia the praeorbital spine is more prominent than the tooth of the 

 basal joint of the external antenna?, j^rojecting over and concealing 

 it; in Pcriccra, on the contrary, tlie antcnnal looth is niDre promi- 

 nent than the prreorbital. 



ll has been usual to place Pcriccra and its allies near the Mciuc- 

 thciiuc, along with Ilaliiiiits and /'iii:;cttia. on the ground of the 

 non-retractility of the eyes. lUit the eyes should scarcely be called 

 non-retractile, when, as may be seen in any wet specimen, they are 

 really more completely retractile than in any otiu'r genus of Maioids, 

 and may be drawn in so far as to be completely hidden. It is true 

 that ilii.-- is not a folding back, as in Hyas and Iiiac/ms. but a direct 



