PART 1 garth: pacific oxyrhyncha 351 



pointed teeth or into spines. Stiff, short hairs almost entirely concealing 

 these indentations. (A. Milne Edwards, modified) 



The male first pleopod is decidedly mithracine, resembling in par- 

 ticular that of Mithrax (Mithrax) tuberculatus in having a bulbous 

 base, a pointed tip, and two triangular lateral projections, in one of 

 which the aperture is situated. (See Plate V, figs. 1, 2) 



Specimens from Secas Islands, Panama, differ uniformly from those 

 of other localities, both north and south, in that laminiform processes of 

 the carapace are lacking. In their place are blunt spiniform teeth well 

 separated at their bases. A small but distinct tridentate lobe in the 

 posterolateral region constitutes the only approach to a crest in the entire 

 armature. 



Material examined: 120 specimens from 31 stations. (See Table 70) 

 From the southeast end of Cholla Bay, Sonora, Mexico, Bruce W. 

 Halstead, collector, to Bahia Honda, Panama. In addition to the above, 

 two females from Tepoca Bay, Gulf of California, Mexico, April 25, 

 1921, Fred Baker, collector, California Academy of Sciences, determined 

 by M. J. Rathbun ; also one male from Utria Bay [Port Utria], Colom- 

 bia, Askoy Expedition. (Garth, 1948) 



Measurements: Male: length 29.6 mm, width 33.8 mm, rostrum 

 5.0 mm, width 4.4 mm, cheliped 29.2 mm, chela 13.2 mm, dactyl 6.0 

 mm, height of palm 4.3 mm, ambulatory legs 29.0, 25.0, 22.5, and 

 19.0 mm, respectively. Female: length 33.0 mm, width 40.0 mm. 



Color in life: Olive green overgrown with white bryozoans, green 

 and purple sponges and algae. Eggs purplish black. (Crane, of a specimen 

 from Chamela Bay, Mexico) 



Habitat: Under side of stones at extreme low-tide level, in tidepools 

 and in Pocillopora coral. (Crane) Associated with the hatchet clam 

 Pinna. (Steinbeck and Ricketts) Typically covered with calcareous algae, 

 sponges, hydroids, bryozoans, serpulids, barnacles and sand grains. 

 (Crane) Velero III specimens were collected 18 times on rocky shore, 

 cracked 5 times from Pocillopora coral, and dredged three times on bot- 

 toms of sand, sandy mud, or coralline. 



Depth: Shore to a maximum of 12 fathoms. 



Size and sex: Males from the Gulf of California are from 12.1 to 

 29.6 mm, females from 12.5 to 33.0 mm, ovigerous females from 23.0 

 to 33.0 mm. Males from the Bay of Panama (including Costa Rica) 

 are from 7.0 to 21.6 mm, females from 6.4 to 16.6 mm, and ovigerous 

 females from 12.5 to 15.3 mm. Thus it will be seen that females of a 

 size that in the Gulf of California would be immature are breeding in 

 the Bay of Panama. 



