PART 1 GARTH : PACIFIC OXYRHYN'CHA 361 



boldt Bay, Askoy (Garth). Ecuador: off Esmeraldas, Askoy (Garth). 

 Atlantic analogue: Possibly Mithrax (Mithrax) pleuracanthus 

 Stimpson. 



Diagnosis: Rostral lobes broad and arcuate, each with three supple- 

 mentary spinules. Four anterolateral protuberances, the last acute and 

 single, the others subdivided into two or three spines each. Three spines 

 on basal segment of antenna. Manus of male inflated, smooth. Tip of 

 male first pleopod pointed, a soft subterminal flap folding inward, form- 

 ing a groove. 



Description : Carapace ovate, a little longer than broad, covered with 

 low tubercles, some bearing one or two granules ; cervical and cardiac 

 groove deep. Edge of marginal prominences granulate. Rostral lobes 

 short, broad, arcuate, separated by a narrow U-shaped sinus. Besides the 

 preorbital lobe, the orbit having two small teeth above, a well-marked 

 outer lobe and two strong teeth below, outside the antenna. Anterolateral 

 protuberances behind the orbit four, the last one at the lateral angle, 

 simple and acute, the others lobiform with subacute tips, but subdivided 

 into two or three ; the first or hepatic lobe the most prominent, the next 

 lobe the widest. A postlateral tubercle present. In a dorsal view, a row 

 of subbranchial spines partially visible. 



Basal antennal article tridentate, all the teeth visible from above, 

 the two outer teeth subequal, the one at the outer angle well behind the 

 rostrum, the tooth at base of second article small. Two subhepatic gran- 

 ules. 



Chelipeds of adult male much longer and heavier than legs. Merus 

 tuberculous and spinous, three or four spines along the inner margin, 

 five or six along the outer, two rows of spines or tubercles on upper 

 surface, one row on outer surface. Carpus granulate. Manus smooth, 

 inflated. Fingers short, stout, gape of male short, a small, acute tooth 

 near base of dactyl, both fingers crenulate, the propodal finger through- 

 out, the dactyl from tip to tooth. Legs furnished with fine, scattered 

 hairs and with spines above. (Rathbun, 1925) 



Material examined: 99 specimens from 34 stations. (See Table 73) 

 From Puerto Refugio, Angel de la Guarda Island, to San Lorenzo Chan- 

 nel in the Gulf of California ; Socorro Island, Mexico ; and from Secas 

 Islands, Panama, to La Plata Island, Ecuador. 



Measurements: Largest specimen, male: length 16.6 mm, width in- 

 cluding spines 15.9 mm, without spines 14.4 mm, rostrum 1.8 mm, 

 width 3.0 mm, chelipe'd 19.S mm, chela 9.6 mm, dactyl 3.9 mm* height 



