PART 1 GARTH : PACIFIC OXYRHYNCHA 341 



island endemic species of the Old World genus Paramithrax. They are 

 more primitive than the Mithracinae both in configuration of orbit and 

 structure of male first pleopods. Maiopsis shares with Oregonia and 

 Hyas of the Oregoniinae a broadened terminal male abdominal segment. 



Key to the American Genera of the Restricted Subfamily 



Majinae Balss 



(Pacific genera are shown in bold-face type and are treated in this work) 

 (Intercalated spine present; basal antennal article not forming floor 



of orbit) 



la. Cardiac lobe not delimited by a deep trench 



2a. Carapace broadly ovate-triangular. Basal antennal article 

 very broad, three-spined. Rostral horns each with an acces- 

 sory spine Maiopsis 



2b. Carapace oblong-triangular. Basal antennal article of mod- 

 erate width, two-spined. Rostral horns simple 



Paramithrax 



lb. Cardiac lobe delimited laterally and posteriorly by a deep 

 trench Temnonotus 



Genus MAIOPSIS Faxon 



Maiopsis Faxon, 1893, p. 150; 1895, p. 11. Rathbun, 1925, p. 337. 



Type: Maiopsis panamensis Faxon, by monotypy. 



Description: Carapace subtriangular, as broad as long, spinose; 

 rostrum produced anteriorly into two divergent horns with an accessory 

 spine upon their outer margins; interorbital space broad. Eyes small, 

 eyestalks slender, retractile within the orbits. Orbits large, with a for- 

 ward aspect, incomplete below, the upper margin prominent, with 

 two deep fissures, and supraocular spines. Epistome short. Basal segment 

 of antennae very broad, with three prominent spines upon its anterior 

 margin ; flagellum of the antennae widely separated from the cavity of 

 the orbit by a broad process of the basal segment. Merus of outer 

 maxillipeds notched at the anterointernal angle. Legs of moderate length ; 

 carpus of chelipeds elongated, not carinated ; chela elongated and slender, 

 fingers canaliculate within, but not spoon-shaped at their tips, their pre- 

 hensile edges meeting throughout most of their length, not distinctly 

 toothed; ambulatory legs spinose. 



Male abdomen seven- [segmented], terminal segment short and 

 broad. (Faxon) 



