PART 1 GARTH : PACIFIC OXYRHYNCHA 311 



Type locality: Galapagos Islands, 6 fathoms, sandy mud; Hugh 

 Cuming, collector. 



Localities subsequently reported, with collectors: Galapagos Islands: 

 James Island, Hassler (Rathbun, 1925) ; Hood, Albemarle, Charles, 

 and James Islands, Velero HI (Garth). 



Atlantic analogue: None. A Galapagos endemic species. 



Diagnosis: Carapace posteriorly produced, four prominent spines on 

 lateral margin. Palm of adult male with a double crest of spines ; ambu- 

 latory legs exceeding chelipeds in length, non-spinulous. Apex of male 

 first pleopod notched as in Herbstia pubescens, but with a straighter keel 

 beneath; both keel and lobe above setigerous. 



Description: Carapace pyriform, moderately depressed, regions 

 slightly raised above general level, surface evenly covered with soft, 

 short pubescence. Rostrum composed of two stout horns equal in length 

 to their combined basal width, their spinulous tips incurving, separated 

 by a broad median notch reaching half way to their bases, and each 

 surmounted by a low ridge bearing, in addition to the usual double row 

 of curled setae, an inner row of short, stiff hairs. Slope of rostrum broken 

 by the acute preorbital spine ; outer margin of spine continuing without 

 interruption to the broad, transverse interorbital tooth ; this tooth form- 

 ing with the acute exorbital a vestibule for the retraction of the reniform 

 cornea. Anteroexternal spine and antennal flagellum, also tip of outer 

 basal antennal spine, visible beyond cornea when retracted. 



Anterolateral margins with four equidistant conical spines or sharp- 

 ened granules, the first and largest hepatic, the remaining three branchial. 

 Below the hepatic spine three pterygostomian spinules, between the first 

 and second branchial spines several spinulous granules at a slightly lower 

 level. Gastric and cardiac regions broadly rounded and set off from 

 adjacent branchial regions by shallow sulci and from each other by a low, 

 transverse, genital ridge. Intestinal region projecting conspicuously be- 

 yond posterior margin, slightly acuminate, and tipped with a small, 

 sharp granule. 



Basal antennal article twice as broad basally as medially, the lateral 

 extension forming the floor of the orbit and bearing the second of two 

 lateral marginal spines, the first or anteroexternal the longer and more 

 forwardly directed. Merus of external maxillipeds triangular, antero- 

 external angle subrectangular, anterointernal angle acute ; merus notched 

 to receive palpus. 



Cheliped of male only slightly more robust than walking legs ; merus 

 with three rows of compound spinules, two inferior and one superior, 



