84 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 5 



the latter reveals a similarity greater than one would be led to expect from 

 written descriptions only, in that antennal and orbital regions, chelipeds, 

 and maxillipeds conform to a remarkable degree. 



An interesting note made by Dr. Waldo L. Schmitt at the time of 

 capture, "cracked from rock," furnishes a possible clue to the use made 

 of the channeled carpi. If this crab inhabits rocky crevices into which it 

 wedges itself securely, may not the ambulatory legs, when held tightly 

 against the under side of the carapace, form gutters for the incurrent 

 and excurrent sea water, effective as prolongations of the afferent and 

 efferent branchial channels? 



This species is dedicated to Mr. Anker Petersen, scientific artist, in 

 the full realization that he has depicted it more accurately in line and 

 stipple than I can hope to do in words. 



Genus PILUMNOIDES Milne Edwards and Lucas 



Pilumnoides rotundus, new species 

 Plate 23, Figs. 1-5 



Type: Female, holotype. Cat. No. 374, Allan Hancock Foundation, 

 The University of Southern California, from San Esteban Island, Gulf 

 of California, Mexico, 35 fathoms, shell; March 27, 1937; collected by 

 Allan Hancock Expedition of 1937 at Velero Station 729-37. Male, I 

 allotype, Cat. No. 374a, from south end of Tiburon Island, Gulf of 

 California, Mexico, 8-10 fathoms, kelp, corallines; March 10, 1936; 

 collected by Allan Hancock Expedition of 1936 at Velero Station 564-36. | 

 Three females and one young, paratypes, from San Francisquito Bay, 

 Lower California, Mexico, 165 fathoms, shale and mud; March 1, 1936; j 

 and one female, ovigerous, paratype, from the same locality, 125 fathoms, \ 

 shale, rock, and mud; March 2, 1936; collected by Allan Hancock Ex- 

 pedition of 1936 at Velero stations 529-36 and 534-36, respectively. 



Measurements: Female holotype: length of carapace 7.4 mm., width 

 8.8 mm., of fronto-orbit 5.2 mm., length of major manus 4.9 mm., height 

 3.5 mm. Male allotype: length 7.4 mm., width 8.7 mm. 



Diagnosis: Carapace granulate posteriorly as well as anteriorly. Ob- ji 

 lique prolongation from lateral angles wanting. Orbits with superior 

 fissures obliterated. Merus of third maxilliped produced at outer distal 

 angle. Manus externally hairy. 



Description: Carapace suborbicular, rotund, slightly broader than 

 long, and narrowing posteriorly. Regions well defined anteriorly, oblit- 



