PODOCERIDAE 247 



Podocerus, sp. (Fig. 155). 



Occurrence: St. 42. South Georgia. 1 immat. 4 mm. 



Remarks. Dorsal profile somewhat resembling that oidanae, Stebb. (1888, pi. cxxviii), 

 but the projections are not keels so much as corrugations or transverse ridges on the 

 hind margins of the segments. The ridges are slightly more raised medio-dorsally into 

 tubercles on peraeon segments 4-7 and pleon segment 1, and there are very faint 

 indications of a smaller dorso-lateral tubercle on each side. 



Fig. 155. Podocerus, sp. St. 42. Dorsal profile. 



Gnathopod 2, 6th joint subcircular, palm defined from hind margin only by a small 

 tooth. Peraeopods 1 and 2, 2nd joint slender, linear. Peraeopods 3-5, 2nd joints feebly 

 pyriform, slightly wider proximally than distally. 



With only one immature specimen (probably <$) it is not advisable to assign a specific 

 name in this case. 



Gammarideorum incertae sedis 



Didymochelia, Brnrd. 

 Barnard, 193 1, p. 429. 



No rostrum. No eyes. Side-plates well developed, 4 feebly emarginate behind, 



5 bilobed. Pleon segments 5 and 6 very short. Telson transversely oblong, entire. 



Antenna 1 stout, with a short accessory flagellum. Mouth-parts prominently projecting. 



Upper lip elongate, narrow. Lower lip with acuminate outer lobes and very small 



mandibular processes, without inner lobes. Maxilla 1 , inner lobe setose along whole 



inner margin, palp obscurely 2-jointed. Maxilla 2, inner lobe with oblique row of setae 



as well as the marginal row. Gnathopods 1 and 2 not strong, chelate. Peraeopods 1-5 



alike, stout. Uropods 1 and 2 stout, biramous. Uropod 3 rudimentary, consisting of 



a small ovate peduncle only. 



Remarks. It is difficult to decide on the affinities of this Amphipod. Several of its 

 features, such as the projecting and somewhat pointed mouth-parts, the similarity of 

 the peraeopods, and the reduction of uropod 3, would seem to be due to its habitat and 

 mode of life in the galleries of sponges. There is some resemblance in general body form 

 to the aberrant Lysianassid Pachychelium, but the only features which may really be said 

 to be Lysianassid are the 1st antenna and the lower lip. Gnathopods 1 and 2 bear a 

 remarkable resemblance to those of Pariphimedia integricauda, Chevr.; and in some 

 respects the mouth-parts also are not unlike. In fact it would perhaps not be incon- 

 sistent to include this Amphipod in the Acantonotozomatidae, but for the presence of 

 the accessory flagellum. This latter feature also militates against placing it in the some- 

 what heterogeneous group of genera comprising the Calliopiidae. On the whole I am 

 rather inclined to include it among the Lysianassidae. 



