COMPLETE HAIG : EASTERN PACIFIC PORCELLANIDAE 223 



in frontal view, the lateral lobes narrow, truncate, median lobe nar- 

 row, triangular, rounded at tip, lobes separated by deep, rounded 

 notches, the three about equally projecting. Eyes visible in dorsal view. 



First and second movable segments of antenna roughly granular; 

 third more or less smooth; flagellum naked or with vestigial hairs 

 visible only under magnification. Outer maxillipeds roughly rugose. 



Chelipeds covered with small, coarse granules, naked or lightly pub- 

 escent. Merus with a low, granular lobe on anterior margin ; dorsal sur- 

 face eroded, sometimes deeply so. Carpus about one and a half times 

 as long as wide, with a broad, low, triangular tooth occupying proxi- 

 mal third of anterior margin ; surface with four longitudinal rows of 

 large, often deep pits, giving surface an eroded appearance. Manus with 

 three longitudinal crests on dorsal surface and a fourth along outer 

 margin, these crests defined by broad grooves containing rows of pits, 

 usually less marked than those of carpus. Gape of fingers naked or 

 lightly pubescent. 



Walking legs slender, granular and pitted, and with scattered, short 

 plumose and non-plumose hairs. Anterior margin of merus, carpus, 

 and propodus with a high crest. 



Telson of abdomen with seven plates. 



Material examined: See Table 67. 



Measurements: Males, 2.3 to 6.2 mm; non-ovigerous females, 2.4 to 

 5.9 mm. The female holotype measures 5 mm in length, 5.2 mm in 

 width. 



Color: The color in alcohol is light pink, according to Glassell 

 (1936). Specimens examined by the writer were pale buff to nearly 

 white. 



Ecology: Megalobrachium erosum has been dredged in depths of 5 

 to 25 fathoms. Specimens taken by the Velero III and IV were from 

 bottoms of sand and of sand with nuUipores, two stations each; and 

 shell and sand ; rock and sand ; coralline and nullipores, one station each. 

 Glassell (1936) gave no information on substrates for the type series, 

 but remarked: "The difficulty of obtaining undamaged specimens is due 

 not only to its small size, but also to the hard materials which are brought 

 up in the dredge with it." 



No ovigerous females have been collected. 



Range: Punta Malarrimo south to Bahia de la Magdalena, Baja 

 California; Gulf of California, from Isla Angel de la Guarda south 

 to Bahia de La Paz; Isla Isabel. 5 to 25 fathoms. 



