NO. 3 BARNARD : THE PHOXOCEPHALIDAE 191 



prolonged posteriorly. In males, the posterior edge may become quite 

 convex and distorted (Plate 11, fig. F). 



In one facies of P. obtusidens the posterior edge is concave and 

 slightly prolonged so that the lower corner is slightly produced in both 

 sexes and quite heavily setose along the posterior edge. 



One group of species, represented by P. calcaratus has few setae on 

 the posterior edge of the epimeron but bears a diagonal row of setae 

 along the lateral face of the segment (Plate 26, fig. U). This feature 

 is easily overlooked and several species need reexamination on this point. 



Minor Systematic Differences in Paraphoxus 



In general, the following criteria are not used by the writer for 

 basic diagnoses of species. Occasionally they may be useful as peculiarities 

 not generally found in the group. Some of these characters may have 

 important future use for helping to distinguish lines of evolution in 

 the genus. 



Mouthparts. — Generally these are uniform in the group but two 

 points of interest should be noted. 



The molar of the mandible in some species such as P. lucubrans 



(Plate 12, fig. F) is more bulbous than in others. This difference is 



difficult to observe without careful preparation of the mandible and 



is subject to artifacts according to the tonicity of the mounting 



media used and the kind of preservation. 



The fourth article of the maxillipedal palp varies from species 

 to species depending on the appearance or absence of an apical spine. 

 Various states of fusion of this spine occur so that its use as a subgeneric 

 character was abandoned by the writer. This character may help in 

 determining lines of evolution and it should be checked in many of 

 the poorly known species. 



Coxae. — The number of setae on the coxae may be useful on a 

 minor scale to differentiate species but care must be used, as in so many 

 of the criteria discussed, that ecological conditions do not play a part 

 in the expression of them. In P. milleri, cusps on the coxae are a 

 distinctive feature (Plate 40, fig. H). 



Peraeopods 1 and 2. — The spines of the posterodistal end of article 

 5 may be quite slender as in P. milleri or quite stout as in most of the 

 other species. 



Second phonal epimera. — Most of the species have the lower 

 posterior corner rounded and the posterior edge smooth. However in 

 one larger species, P. obtusidens major, the lower corner is produced 



