72 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



Petrolisthes rathbunae Schmitt 

 Plate 26, fig. 2 



Petrolisthes rathbunae Schmitt in Hilton, 1916, p. 72 (listed only), 

 text-fig. 6 (not recognizable to species). Schmitt, 1921, p. 181 

 (description; type locality, San Clemente Island, California), pi. 

 32, fig. 3. Glassell, 1938a, p. 443. Hewatt, 1946, pp. 191, 195, 

 200. 



Previous records: California. Monterey Bay; Santa Rosa Island: 

 (Schmitt). Scorpion Harbor and between Pelican Bay and Prisoner's 

 Harbor, Santa Cruz Island: W. G. Hewatt and W. Williams (Hewatt). 

 Santa Monica Bay; San Pedro Bay: (Schmitt). Laguna Beach: W. 

 A. Hilton (Hilton). Santa Catalina Island: (Schmitt). San Clemente 

 Island: H. N. Lowe (Schmitt). 



Diagnosis: Carapace with short, transverse, piliferous striations; 

 no epibranchial spine; front triangular; carpus about two and a half 

 times as long as wide, anterior margin sometimes spinuliferous, mar- 

 gins subparallel ; merus of walking legs without spines on anterior mar- 

 gin, that of leg 1 with a very small spine at posterodistal angle. 



Description: Carapace completely covered with short, transverse, 

 piliferous striations, latter taking the form of large, flattened, imbricate 

 tubercles on epibranchial region and smaller granules on front; regions 

 distinct. Front triangular, with a deep median sulcus; no supraocular 

 spine; inner orbital angle not produced. Outer orbital angle slightly 

 produced. No epibranchial spine. 



First movable segment of antenna with a strongly projecting, gran- 

 ular, lamellar lobe, the granules produced into spinules in small speci- 

 mens; second roughly granular or rugose, armed with a distal spinule 

 on anterior margin in small specimens; third roughly granular; flagel- 

 lum with short hairs sometimes visible only under magnification. Outer 

 maxillipeds rugose. 



Chelipeds lightly pubescent. Merus rugose, armed on anterior mar- 

 gin with a strongly projecting rugose lobe. Carpus about two and a half 

 times as long as wide, margins subparallel, covered with large flattened 

 granules, some of the granules along anterior margin produced into 

 spinules in small specimens; surface with a low median longitudinal 

 crest covered with enlarged granules ; posterior margin with an obliquely 

 rugose crest ending distally in a sharp tooth. Manus granular, with a 

 thin outer edge; inner margin with large, oblique, flattened tubercles. 

 Dactylus with a longitudinal median crest composed of imbricate tuber- 



