PART 1 GARTH : PACIFIC OXYRHYNCHA 305 



Habitat: The twelve stations for which data on substratum are 

 available are equally divided between rock and [Pocillopora] coral. 



Depth: Shore or from coral heads in shallow water. To 4.5 fathoms. 

 (Rathbun, 1924c) 



Size and sex: The present series contains males of from 7.0 to 21.6 

 mm, females of from 5.6 to 14.1 mm, ovigerous females from 9.9 to 

 14.3 mm. Since there are no males between 14.1 and 21.6 mm, and the 

 14.1 mm male fails to show the digital tooth, the size at which this sec- 

 ondary sex character is attained cannot be stated. 



Breeding: Seven of eight females encountered by the Velero III 

 at Isabel Island, Mexico, in March were ovigerous. 



Remarks: With the exception of the cotype from Acapulco (M.C.Z. 

 No. 991) and a young female from Patos Anchorage (Calif. Acad. 

 Sci.), Rathbun (1925, p. 295) was obliged to rely on citations of non- 

 extant specimens for most of the locality records given for this species. 

 To make matters more difficult, these were recorded by Lockington 

 under different names, and one must look to a third party, S. J. Holmes, 

 who saw Lockington's types, for assurance that one is dealing in each 

 case with the same organism. Even Holmes was misled into including 

 southern California and west coast of Lower California material under 

 Stimpson's species ; these are now separated from Gulf of California and 

 Mexican specimens and listed under Herbstia parvifrons Randall. 



Early in his studies of the Hancock collections the writer had occa- 

 sion' to compare specimens from both the Gulf of California, station 

 604-36, and southern Mexico, station 261-34, with the female holotype 

 of Mithrax (Mithrax) sonorensis, U.S.N.M. No. 67865. At a much 

 later date their agreement with the original description of Herbstia 

 camptacantha was noted and the identity of the two strongly suspected. 

 The elongated propodal segments of the ambulatory legs are character- 

 istic of Herbstia, rather than of Mithrax. A study of the male first 

 pleopod of Mithrax sonorensis clearly shows it to be pisine, rather than 

 mithracine, in character. M. (Mithrax) sonorensis Rathbun is there- 

 fore considered a synonym of Herbstia camptacantha (Stimpson). 



The Hancock expeditions series confirms Lockington's Gulf of Cali- 

 fornia localities for the species and extends the range southward from 

 Acapulco, Guerrero, to Tangola-Tangola, Oaxaca, Mexico. 



