PART 1 GARTH : PACIFIC OXYRHYNCHA 445 



Description: Carapace an equilateral triangle, the posterior margin 

 being nearly straight, and scarcely exceeding the anterolateral [mar- 

 gins] in length, resulting from the strong projection of the dentated 

 posterior corners of the branchial regions, almost concealing the ambu- 

 latory [legs]. Anterolateral margin with about twelve very small gran- 

 ulated teeth, three on the small rounded hepatic region. Surface orna- 

 mented with conical tubercles variable in number and size. Rostrum 

 prominent, obtuse, triangular. Base of the movable part of the external 

 antennae protected on each side by an over-arching tooth, one arising 

 from the lower margin of the orbit, the other from the anterior corner 

 of the epistome. In the outer maxillipeds the ischium granulated, the 

 merus tuberculated. 



Chelipeds rather short, strongly angular and dentated; hand gran- 

 ular below, but nearly smooth above between the high and unevenly 

 eight- or nine-toothed crests; the teeth denticulated, the middle one 

 largest. Ambulatory [legs] perfectly smooth and glabrous; dactyli 

 pubescent. (Stimpson, modified) 



Male abdomen constricted between fifth and sixth somites, sixth 

 somite with a prominent proximal median tooth, seventh somite broader 

 than long, sides slightly concave. Female abdomen granulate and hairy, 

 lacking prominent ridges or tubercles, middle portion set off from lateral 

 portions by shallow longitudinal sulci. 



Material examined: 47 specimens from 17 stations. (See Table 96) 

 From Magdalena Bay, Lower California, and Puerto Escondido, Gulf 

 of California, Mexico, to off La Plata Island, Ecuador, including 

 Socorro and Clarion of the Revilla Gigedo Islands, but excluding the 

 mainland from Mexico to Ecuador. In addition to the above, 44 speci- 

 mens from 17 Galapagos Islands stations (Garth, 1946). 



Measurements: Largest specimen, male: length 13.7 mm, width in- 

 cluding spines 17.7 mm, rostrum 1.7 mm, width 2.5 mm, exorbital width 

 5.9 mm, cheliped (right) 24.0 mm, merus 8.0 mm, manus 13.1 mm, 

 dactylus 6.0 mm, height of palm 6.9 mm. Female specimen: length 12.0 

 mm, width including spines, ca. 15.0 mm (spine broken). 



Color in life: See Garth (1946, p. 411). 



Habitat: Sand with rock and coral; rock. (Garth, 1946) Of the 17 

 stations from localities other than Galapagos, bottoms were sand in 10 

 cases, with nullipores, algae, and coralline algae present in descending 

 order of frequency in more than half; rock in 3 cases, with nullipores 

 in 2; and organic bottoms in 4 cases, with shell, coralline algae, and 



