224 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



Megalobrachium peruvianum, new species 

 Plate 16, figs. 1-3, 9; plate 40, fig. 1 



Types: Holotype, male, U. S. National Museum Cat. No. 102413, 

 from Islas Lobos de Afuera, Peru, rocky shore; January 17, 1935; 

 collected during Allan Hancock Pacific Expedition of 1935 at Velero 

 III station 391-35. Paratypes: same data as holotype, one male, two 

 ovigerous females (U. S. National Museum) ; one male, two females 

 (one ovigerous) (Allan Hancock Foundation). Paratype: Junin, Chile, 

 shore; December 10, 1904; collected by R. Paessler; one male (Ham- 

 burg Museum Cat. No. K7739). 



Diagnosis: Carapace nearly smooth; lateral margins rounded; front 

 with three teeth separated by deep, rounded notches; carpus less than 

 one and a half times as long as wide, anterior margin with a small, 

 triangular projection at anteroproximal angle, surface with longitudinal 

 crests; manus with longitudinal crests; telson with seven plates. 



Description: Carapace about as broad as long, very strongly con- 

 vex front to back ; covered with small, flattened granules and appear- 

 ing nearly smooth, posterolateral regions with light plications and punc- 

 tae, a few scattered, larger granules near lateral margins; regions not 

 distinct ; surface lightly pubescent. Front strongly produced beyond 

 eyes, rounded or broadly triangular in dorsal view; tridentate or strong- 

 ly trilobate in frontal view, lateral lobes rather broad, truncate, median 

 lobe narrow, triangular, rounded at tip, lobes separated by deep, rounded 

 notches, the three about equally projecting. Eyes very small, usually 

 visible in dorsal view. 



Movable segments of antenna smooth or lightly granular; flagellum 

 with vestigial hairs visible only under magnification. Outer maxillipeds 

 nearly smooth. 



Dorsal surface of chelipeds covered with small granules, a little 

 larger and more distinct than those of carapace, and particularly out- 

 standing on crests; granules somewhat enlarged and flattened on ven- 

 tral surface; dorsal surface naked or lightly pubescent. Merus with a low 

 but distinct, rounded, granular lobe on anterior margin. Carpus less 

 than one and a half times as long as wide, anterior margin unarmed, 

 somewhat sinuous, with a slight triangular projection at anteroproximal 

 angle; dorsal surface with three low, longitudinal crests, the first near 

 anterior margin, second about center, third just posterior to it, 

 second and third not extending to distal end of carpus; posterior margin 

 markedly convex, with a low longitudinal crest, the latter and dorsal 



