162 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



3a. Rostrum long, greatly advanced beyond orbits; preoc- 

 ular spine twice length of remainder of orbit. Legs 

 filiform. First movable article of antenna cylindrical 



Picroceroides 



3b. Rostrum short, little if any advanced beyond orbits; 



preocular spine not long. Legs moderately robust. First 



movable article of antenna flattened . . Pitho 



lb. Orbit unprotected below; eyes protected above by a lamellate 



projection consisting of the supraocular eave and an outgrowth 



of the hepatic region 



4a. Basal prolongation of exognath of third maxilliped curving 

 forward and usually lodged in a groove of the ischium of 

 the endognath. Abdomen seven-segmented in both sexes 



Tyche 



4b. Basal prolongation of exognath of third maxilliped not re- 

 curving; merus of endognath strongly arched, brilliantly 

 glistening, and porcellanous. Abdomen of female with seg- 

 ments 4-6 coalesced Stilbognathus 



Genus PITHO Bell 



Pitho Bell, 1835b, p. 172. Rathbun, 1925, p. 355. 



Othonia Bell, 1836, p. 55; type: Pitho sexdentata Bell, 1835, by subse- 

 quent designation of Miers (1879c, p. 665). 

 Piloronus Gistel, 1848, p. X (name substituted for Pitho Bell, believed 



preoccupied by Pytho Fabricius). 

 Engyzomaria Gistel, 1848, p. X (name substituted for Othonia, preoc- 

 cupied). 

 Microrynchus Desbonne, 1867, p. 20; type: M. Iherminieri Desbonne, 

 1867, by monotypy. 

 Type: Pitho sexdentata Bell, type of Othonia Bel\=Pitho Bell, by 

 subsequent designation of Miers (1879c, p. 665). 



Description: Carapace truncate in front; frontal region broad, ros- 

 trum very short and formed by two small teeth. Orbits small, tubular, 

 and deep; eyes slender. External antennae short; their basal article 

 lamellate and forming the floor of the orbit ; the second article flat, short 

 and broad, especially in its terminal portion ; the third article flattened, 

 but smaller; the movable flagellum much reduced. Stiff, straight hairs 

 bordering the external antennae, and appearing in series and in regular 

 tufts on the pterygostomian regions. Carapace suboval, the anterolateral 



