] 76 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



The name, derived from the Greek KAaaros, broken in pieces, and 

 Toixos, a wall, was suggested by the fragmented side walls of the 

 carapace characteristic of members of this genus. 



Clastotoechvis diffractus (Haig), new combination 

 Plate 30, fig. 1 ; text-fig. 5(1) 



Petrolisthes diffractus Haig, 1957a, p. 36, pi. 9, figs. 1-6 (type locality, 

 San Lorenzo Rocks, Acapulco, Mexico). 



Previous records: Mexico. Bahia Tenacatita: (Haig). San Lorenzo 

 Rocks, Acapulco: J. S. Garth from Velero IV (Haig). 



Diagnosis: Lateral lobes of front truncate, not markedly elongate; 

 orbits angular, strongly oblique; carpus with four broad, strongly pro- 

 jecting teeth on anterior margin, surface with a low crest; outer margin 

 of manus with brush of hair usually present in females only. 



Description: Carapace covered anteriorly with large, flattened, im- 

 bricate granules, smaller on frontal region, and posteriorly with elon- 

 gate rugae; regions not distinct. Frontal region slightly depressed; 

 frontal lobes extending beyond eyes, median lobe triangular and 

 rounded at tip, lateral lobes truncate; in dorsal view the three lobes ap- 

 pearing to be about equal in length, but in frontal view the median one 

 showing a long, acute, strongly deflexed extension. Orbits angular, 

 strongly oblique; on either side a small, pointed preorbital lobe sep- 

 arated by a notch from lateral frontal lobe; outer orbital angle pro- 

 duced, pointed at tip. Rugae and granules of carapace setiferous on their 

 anterior side, hairs not visible except under magnification. 



First movable segment of antenna with a strongly projecting, finely 

 granular lamellar lobe; second with a double row of large, strongly 

 projecting nodules on anterior margin, and scattered smaller granules 

 on surface ; third more or less smooth ; flagellum naked or with vestigial 

 hairs, latter longer toward distal end. Outer maxillipeds rugose. 



Merus of chelipeds covered with flattened setiferous granules, an- 

 terior margin with a small pointed lobe, only slightly produced. Carpus 

 one and a half to two times as long as broad, covered with rough, 

 rounded granules, more projecting than those of carapace, and with a 

 short, fine pubescence not obscuring granules; anterior margin with 

 four broad, strongly projecting, granular teeth, proximal one at right 

 angle to carpus, others tilted progressively forward, with the distal 

 tooth, formed of a projection of the anterodistal angle, lying nearly 

 parallel with the long axis of the carpus; surface with a low longitudi- 



