332 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



Habits. Dodge about rocks that are awash at high tide and hide 

 in crannies when pursued. Also at home on drift timber in the 

 open sea, which accounts for the wide range of some of the species. 



Distribution. All warm seas; extends into the Mediterranean. 



KEY TO THE AMEKICAN SPECIES OP THE GENUS PLAGUSIA. 



A 1 . Carapace tuberculate. Merus joints of legs unispinose anteriorly. 



B 1 . Tubercles of carapace well marked. Merus joints of legs with two fringes 

 of hair on upper (or posterior) surface. 



C 1 . Coxal joints of legs with a dentate lobe dcprcssa, p. 332. 



C*. Coxal joints of legs with an entire lobe depressa tubcrculata, p. 334. 



B*. Tubercles of carapace depressed, ill-defined. Merus joints of legs with 



only a posterior fringe of hair on upper surface immaculata, p. 335. 



A*. Carapace tornentose, nearly smooth. Merus joints of legs multispinose 

 anteriorly chabrus, p. 330. 



PLAGUSIA DEPRESSA (Fabrieins). 



Plate 101. 



Cancer dcprcssus FABRICIUS, Syst. Entom., 1775, p. 400 (type-locality, in 



mari mcditcrranco; type in Kiel Mus.). 1 

 Cancer sqnamosus HERBST, Natur. Krabben u. Krebse, vol. 1, 1790, p. 260, 



pi. 20, fig. 113 (type-locality, Ostindicn; type in Berlin Mus.?). 1 



Probably confused with P. dcprcssa tubcrculata. 



Grapsus dcprcssus Bosc, Hist. Nat. Crust, vol. 1, an X [1801-1802], p. 203. 

 Playusia dcprcssus SAY, Journ. Acad. Nat. Sci. Philadelphia, vol. 1, 1817, 



p. 100. 

 Plagusia sayi DE KAY, Zool. New York, Crust., 1844, p. 16 (type-locality. 



Gulf stream; type not extant). . 

 Plagusia squamosa LATKEILLE. Encyc. Meth., Hist. Nat., Entom., vol. 10, 



1825, p. 145. 

 Playusia gracilis SAUSSURE, Mem. Soc. Phys. Hist. Nat. Geneve, vol. 14, 



1S3S, p. 449 [33] (type-locality, Cuba; type in Geneva Mus.). 



Diagnosis. Carapace tuberculate. Coxal joints of legs with a 

 dentate Icbe; merus joints with one spine on anterior margin. 



Description. All the regions of the carapace are distinct, and the 

 surface is covered with flat pearly or squamiform tubercles which are 

 fringed anteriorly with small close-set bristles of uniform length. 

 On the front of the gastric region is a series of about six prominent 

 acute tubercles arranged in an arc concave forward. Antero-lat- 

 eral border armed with four teeth (including orbital angle), 

 which in the main decrease in size from before backward. Epistome 

 prominent beyond the anterior border of the carapace and cut usuallj' 

 into five lobes. 



Chelipeds of adult male massive and about as long as carapace, 

 in the female slender and about three-fourths as long as carapace. 



'The supposed type-specimen Is labeled " Alpheus dcpressus P." No locality i Riven. 



*I searched for the type but did not find it. Ililgendcrf, In 1882 (SB. Gcs. Naturf. 

 Freunde Berlin, 1882, p. 24), says that the type-specimen of Cancer squamosus has the 

 lobe at the base of the legs entire, but this is not the case in Herbst's fig. 113. pi. 20. 



