60 Annals of the South African Museum. 



sub-family Trischizostomatina, for which Sars, iu 1882, substituted 

 the family name Trischizostomidae, improved by Bovallius, in 1886, 

 into Trischizostomatidae. In the preface to the report on the 

 Challenger Amphipoda (1888), I remarked that " the Prostom- 

 atidae are in close relationship with the Lysianassidae, and 

 might, in my view, well be included in the older family." This 

 opinion has been fully confirmed by Professor Sars in his " Crustacea 

 of Norway," vol. i., p. 30 (1890). It is unfortunate that Boeck, 

 Bovallius, and Sars, when discussing and figuring the species called 

 T. rascJm, by Boeck, appear to have been in ignorance of Costa's 

 Guerinia nicceensis, so that they have expressed no opinion as to the 

 identity or distinctness of the Norwegian and Mediterranean forms, 

 which until recently I have regarded as specifically one. Delia 

 Valle, on the other hand, has separated them not only specifically 

 but generically, substituting the name Guerina for the preoccupied 

 Guerinia. He admits the great superficial similarity of the two 

 forms, but in his contrasted generic definitions makes out a strong 

 case for keeping them apart. Thus, Guerina has the mandibles 

 with moderately broad trunk, the first maxillae without inner plate 

 and with the palp reduced to a little simple tubercle, the second 

 maxillae with the inner plate short, carrying a single setule, the 

 maxillipeds with the first joint of the palp longer than the second, 

 the first and second peraeopods with the second joint much dilated. 

 Trischizostoma has the mandibles with very narrow trunk, the first 

 maxillifi with inner plate and with minute, slender, two-jointed palp, 

 the second maxillaa with the plates subequal, the inner carrying 

 various little setules, the maxillipeds with the first joint of the palp 

 considerably shorter than the second, the first and second pergeopods 

 with the second joint not dilated. 



Before attributing overwhelming weight to these differences, one 

 must remember that the Scandinavian authors had, among adult 

 examples of their genus, only females to examine, while the three 

 specimens assigned by Delia Valle to his genus were, he says, prob- 

 ably all males. The mouth-organs are very delicate in structure, 

 and, as often happens in tubiform arrangements, not very easy to 

 separate. When successfully drawn apart their appearance, after 

 flattening out, is in some respects extremely different from that 

 which they bore in their natural position. There is also scarcely 

 any doubt that some of the details differ with the age of the 

 specimen. 



Some additional light may be thrown on the question by specimens 

 from South Africa, which certainly require a new specific name, but 



