558 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.38. 



outer antennae without scale, flagellum longer than carapace. Outer 

 maxillipeds operculiform. First, second, and fourth pairs of feet che- 

 late, those of (irst pair largest, unequal, flattened, smooth, and bard; 

 the larger one with arm small, wrist very large, palm of equal width, 

 hollowed out distally next the immovable finder and having a tooth 

 projecting into the wide gape; movable finger with a truncate tooth 

 at its base, extremity hooked; smaller cheliped of first pair much 

 narrower; propodus of third pair obliquely oval. First segment of 

 abdomen narrow; tail-fan broad, telson squarish. 



Length of body about 7 em. The Peruvian specimens are small, 

 about 17 mm. long. The wrist is proportionately longer than in 

 Milne Edwards's ligure and the tooth on the dactyl of the large claw 

 broader. 



Living in the muddy sand of the inside beach at Capon. 



Not previously known from Peru. 

 distribution. — Peru ; Chile. 



PETROLISTHES ARMATUS (Gibbes). 



Plalc II. lig. 3. 



Porcellana armata (Iihbes, Proc. Amor. Ass. Adv. Sci., vol. 3, 1850, p, 190. 

 ParcellanagundlachiiGv±BiN, in LaSagra's Hist. Cuba, vol. 8 (atlas), 1855, Articu- 

 lata, pi. 2, fig. <i. 



Small. Carapace ovate, finely rugose; a spinule on lateral margin 

 behind hepatic sinus. Front triangular, undulated. Eye stalks 

 short and stout, cornea large. Flagellum of antenna much longer 

 than body. Maxillipeds very huge, projecting beyond the front. 

 Chelipeds broad and Hat. subequal but unlike: wrist long, tridentate 

 on anterior margin, two or three spines at distal end of posterior 

 mat gin; palm triangular, widening distally ; fingers shorter than palm, 

 slightly gaping in the stouter chela. First three pairs of legs half as 

 long as chelipeds; uterus joints flattened, spinous; following joints 

 slender. Last pair of legs much slenderer, indexed. Abdomen sym- 

 metrical, bent under the body, sixth segment bearing a pair of lamellar 

 appendages, which with the telson form a swimming fan. 



Width 7 to 8 mm. 



Taken on the \><-m-h at Las Vacas, near < apon, January 23, 1908. "Salamandra." 

 These crabs are found in vast abundance on the shelly oyster hanks bordering the man- 

 grove swamps at Matapalo. The bank is exposed at low tide for a \\ idth of about 25 

 meters. By scratching in the shelly ground many of these crabs can be taken. 



( tyster beds of Matapalo (mar < lapon I, January 23, 1908, from masses of sponge. 



Not previously known from Peru. 



Distribution. — From Lower California to Peru; from Florida to 

 Brazil; Bermudas; [ndo-Pacific region. 



