84 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



Depth: Velero III specimens were obtained in from 5-55 fathoms, 

 exceptionally in 80 fathoms. 



Size and sex: Males in the present series range in size from 8.5 to 



27.7 mm, the latter being the largest on record, females from 6.2 to 



24.8 mm, ovigerous females from 14.0 to 16.3 mm. It should be noted, 

 however, that a 16.4 mm male from the Gulf of California, of a size 

 corresponding to the ovigerous females, which are from the Gulf of 

 California also, has well developed chelae, while specimens of larger 

 size, from the Bay of Panama and Costa Rica, including the male 

 neotype, may retain the slender chelae usually associated with sexual 

 immaturity. 



Breeding: As noted above, ovigerous females were encountered only 

 in the Gulf of California. March was the month in which egg-bearing 

 was observed. 



Remarks: Although the Zaca obtained a larger number of specimens 

 from the Gulf of California, the Velero III dredged the species from a 

 greater number of stations and extended the known range north to 

 Ensenada de San Francisco, near Guaymas, Sonora, Mexico. The records 

 of the Askoy in southern Panama and Colombia were confirmed and 

 stations in northern Panama and Costa Rica were added. It is assumed 

 that the species will be found to occur between Port Parker, Costa Rica, 

 and the Gulf of California wherever soft mud and fine sand occur. 



While the identity of the species has not been in doubt since its 

 recovery by the Albatross in the Gulf of California (Rathbun, 1894), 

 its taxonomic status had to await the rediscovery of Collodes gibbosus, 

 which Bell also included in his genus Microrhynchus, and which Miers, 

 by subsequent designation, made its type. Since the solution of the 

 taxonomic problem involved both species, as well as Stimpson's Collodes 

 granosus, and since all are without surviving type material, it appears 

 within the intent of the Copenhagen Decisions in Zoological Nomen- 

 clature (1953, p. 28, par. 34) that a neotype should be established for 

 each. The specimen selected as neotype for Microrhynchus depressus (see 

 above) is of the opposite sex from the holotype, and while of large size, 

 retains the slender chelipeds of the immature male. With these excep- 

 tions, both of which are provided for in the conditions for the establish- 

 ment of neotypes (Ibid., p. 28, par. 35), the proposed neotype agrees 

 with the description of Rathbun (1925) given above, which is based 

 on the description and figures of Bell (1836). 



Evidence that the species does not occur in the Galapagos Islands, 

 to which it was originally attributed, has been set forth previously on 



