NO. 2 WALTON : THE GENUS PYLOPAGURUS 161 



are near the northern limits of this region, since additional evidence for 

 their southern affinities is afforded by their absence in the extensive 

 collections to the North. It seems quite improbable that they would not 

 have been discovered by the widespread collecting of the Velero III and 

 Velero IV off the coast of Northern Mexico or Southern California if 

 they did occur in the North Temperate Zone. 



P. guatemoci alone appears clearly to fit the distributional pattern of 

 the North Temperate Fauna, with no records of its occurrence south of 

 the 28th parallel. Previously, holmesi was considered to be North Tem- 

 perate also, but the records here given show its distribution to be some- 

 thing of a puzzle. The northern segment of its range corresponds rather 

 closely to that of guatemoci, with a sharp break around the Punta 

 Eugenia area. However, its occurrence in the Gulf of California, and in 

 the presumably tropical southern portion, does not coincide with any 

 expected pattern. Moreover, these southern records are the more anom- 

 alous in that they also represent some of the shallowest records for the 

 species. This is the direct opposite to normal expectation, in that north- 

 ern forms usually occur in progressively deeper (colder) water as they 

 range southward. For the present, this anomaly must remain without an 

 explanation. Possibly it may serve as a useful reminder of the need for 

 more information and spur on the search that will bring a fuller under- 

 standing of this interesting group of crustaceans. 



