COMPLETE HAIG : EASTERN PACIFIC PORCELLANIDAE 13 



12a. Lateral margins of carapace entire posterior to epibranchial 

 angle; fingers not twisted Porcellana 



12b. Lateral margins of carapace with spinules posterior to epi- 

 branchial angle ; fingers on one or both chelipeds twisted out of 

 plane with palm Pisidia 



13a. Carapace about as broad as long; front trilobate to strongly 

 tridentate in frontal view; basal segment of antennules very 

 small, recessed behind front, latter projecting over them like 

 a shelf Megalobrachium 



1 3b. Carapace longer than broad ; front with a broad, rectangular 

 rostral process, visible only in frontal view; basal segment of 

 antennules large, produced anteriorly to fill notches between 

 rostral process and inner orbital angles. . . JJlloaia 



ORTHOCHELA Glassell 1936 



Orthochela Glassell, 1936, p. 296 (type species Orthochela pumila Glas- 

 sell, 1936, by original designation). 



Carapace longer than broad ; lateral margins subparallel, armed with 

 a series of short, forward-pointing spines posterior to cervical groove. 

 Front nearly as broad as carapace, trilobate; lateral lobes directed out- 

 ward, their inner margins lying horizontal, front thus appearing trun- 

 cate on either side of median lobe, latter directed forward, strongly 

 projecting. Orbits directed laterally; eyestallcs large, short, retractile. 



Basal segment of antenna not produced forward to meet anterior 

 margin of carapace; with a long, narrow inward projection, forming a 

 partial suborbital margin. First movable segment nearly concealed be- 

 hind outer orbital angle. 



Basal segment of antennule broad, anterior face truncate. 



Chelipeds large, heavy, subcylindrical; manus normally held more 

 or less straight out in front of carapace, instead of bent sharply at 

 articulation with carpus and directed inward ; fingers very short in 

 relation to manus, opening vertically. 



Walking legs slender, somewhat flattened ; propodus with a single 

 movable spinule at distal end of posterior margin ; dactylus ending in a 

 simple spine, with several movable accessory spinules on posterior mar- 

 gin. 



Telson of abdomen composed of seven plates. 



Contains a single species. 



