258 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Fossil: California Pliocene [not Miocene] : Canoas Creek, southeast 

 of Coalinga, Fresno County (Rathbun, 1908) ; California Pleistocene: 

 Rincon del Potrero, Santa Monica (Rathbun, 1926). 



Atlantic analogue: None. A California- Lower California endemic 

 species. 



Diagnosis: Carapace covered with many small spines. Two spines on 

 hepatic region. Front strongly deflexed. Cheliped of old male exceeded in 

 length by first and second walking legs. Apex of male first pleopod not 

 flaring, tip divided into two closely approximated lobes, an opposing lobe 

 of nearly equal size located in cleft between them. Size large. 



Description: Carapace very broadly ovate, inflated, and covered with 

 small, conical tubercles of nearly equal size. Rostrum a little longer than 

 broad, much deflexed, the horns convex above and below and separated 

 for a little more than half their length. Preorbital spine large, often more 

 or less double pointed; postorbital spine subconical, acute. Thoracic 

 sternum transversely grooved. Carapace covered with short hairs. 



Chelipeds in the male large, tuberculated ; hand oblong, palm inflated, 

 the edges rounded. Ambulatory legs subcylindrical, sparingly tubercu- 

 lated, the antepenultimate [segments] grooved above; a small tubercle 

 near the end of the merus. 



Abdomen of the male contracted behind the third segment, the three 

 following segments of nearly equal width, the fourth slightly wider at 

 the base; fifth and sixth segments nearly equal and longer than the third 

 or fourth; last [segment] subtriangular, but rounded at the tip. 



Abdomen of female broadly elliptical, all the [segments] free; the 

 [segments] increasing in length from the third to the sixth; last [seg- 

 ment] broadly rounded, much broader than long. (Holmes) 



A stout spine on the margin of the hepatic region and another equally 

 large just below the margin. 



The basal antennal article, besides the anteroexternal spine, with a 

 tubercle on the outer margin and another on the anterior margin at the 

 insertion of the next article. (Rathbun, 1925) 



Material examined: 53 specimens from 31 stations. (See Table 51) 

 From Cordell Bank, Marin County, California, to Thurloe Head, 

 Lower California, Mexico. 



Measurements: Largest specimen, male: length 190 mm, width 145 

 mm, rostrum 30 mm, width 20 mm, cheliped ca. 220 mm, merus 90 mm, 

 chela 112 mm, dactyl 58 mm, height of palm 39 mm, ambulatory legs ca. 

 290, 240, 225, and 180 mm. Female: length 114 mm, width 86 mm. 



