PART 1 GARTH : PACIFIC OXYRHYNCHA 249 



as a spine. Eyestalks short. Basal antennal article broad, at any rate at 

 the base, its anterior angle generally produced to form a tooth or spine. 

 Merus of the external maxillipeds, owing to the expansion of its antero- 

 external angle, broader than the ischium, and carrying the palp at its 

 anterointernal angle. Rostrum [except in Neodoclea among New World 

 forms] two-spined. Legs often very long. (Alcock) 



Pleopod 1 medium-stout to slender, usually apically somewhat taper- 

 ing, but apex extremely varying (blunt, acute, filiform, straight, genicu- 

 late, etc.). Pleopod 2 short. (Stephensen) 



Although the key which follows permits the ready separation of the 

 genera into the two groups recognized by Balss (1929, p. 11) as the 

 Pisinae, sensu restr., and the Hyasteniinae, the former with, the latter 

 without the intercalated orbital spine, it should be pointed out that such 

 an arrangement is not sustained by the male first pleopods. These are of 

 two principal types, the one exemplified by Scyra, the other by Pisoides. 

 While the Pacific genera exhibiting the scyriform pleopod (Chorilia, 

 Loxorhynchus, Rochinia (part), Scyra, Libidoclaea) align themselves 

 with the Hyasteniinae of Balss, those possessing the pisoidiform pleopod 

 {Herbstia, Notolopas, Pelia, Pisoides, Rochinia (part)), are equally dis- 

 tributed between his Pisinae and his Hyasteniinae. A smaller third group, 

 consisting of the genera Libinia and Neodoclea, have a male first pleopod 

 similar to that of Stenocionops and Macrocoeloma. For this reason, plus 

 the fact that the presence or absence of the intercalated spine is subject to 

 geographical variation within the single species Notolopas lamellatus 

 Stimpson, the subdivisions of Balss are not adopted here. 



From the subfamily as defined by Alcock and Stephenson above, the 

 genera Hyas and Chionoecetes have been withdrawn because of the 

 resemblance of their male abdomen and filamentous first pleopods to 

 Oregonia. The genus Chorilibinia Lockington does not appear because 

 its type species is considered to belong in Stenocionops. The status of the 

 Asiatic species that have been referred to Lockington's genus is beyond 

 the scope of this paper. 



Key to the American Genera of the Subfamily Pisinae Alcock 

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

 la. Intercalated spine present (Pisinae, sensu restr., Balss) 



2a. Seven free abdominal segments in both sexes 



3a. Rostrum short. Carapace suborbicular or broadly ovate 

 4a. Propodi of walking legs long, dactyli short 



Herbstia 



