514 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



setose only; maxilliped with inner and outer plates well developed, 

 palp composed of four articles; gnathopod 2 larger than 1, article 3 

 of gnathopod 2 short; telson not distinctly split, slightly emarginate; 

 uropod 3 with 2 rami; the inner one, half as long as the outer; all 

 segments of urosome separate. 



Type genus: Beaudettia, new genus. 



Relationship: This unusual, although plain amphipod, combines 

 the characteristics of several families. Superficially it appears 

 to be in the Gammaridae or Photidae but has other characteristics 

 of the superfamily Talitroidea (incl. Hyalidae). 



The lack of a mandibular palp removes the genus from the Gam- 

 maridae and Photidae, but the presence of an accessory flagellum 

 and inner lobes of the lower lip restrict it from the Talitroidea. 



The antennae are those of the Gammaridae; the lateral head lobe 

 and its notch are those of Gammaridae; the mandible is that of 

 Talitroidea; the lower lip is that of the Photidae and Aoridae; both 

 pairs of maxillae differ from those of any of the three mentioned 

 families by the slender lobes ; the maxilliped is not unique ; the gnatho- 

 pods could be those of either Gammaridae or Photidae but incon- 

 ceivably of Talitroidea; the telson is rather unique, not fitting any of 

 the mentioned families, but certainly closer to Photidae than the 

 others; the third uropod is peculiar, like that of some Photidae 

 but it could be one of the Gammaridae highly modified; the segrega- 

 tion of urosomal segments among numerous other criteria separates 

 the family from the Dexaminidae. 



If the species had a mandibular palp, I would place the genus in 

 the Photidae but this would obscure its special characters such as the 

 head lobe notch and the very slender maxillae, which resemble Gam- 

 maridae more than Photidae. 



Beaudettia, new genus 



Diagnosis: With the characters of the family. 

 Type species : Beaudettia palmeri, new species. 



Beaudettia palmeri, new species 



Figures 19, 20 



Diagnosis: With the characters of the family. 



Description: Article 2 of antenna 1 as long as article 1, article 3 

 two-thirds as long as article 2, accessory flagellum stout, short, com- 

 posed of a long article tipped with a short one; antenna 1 much 

 longer than antenna 2, the antennae otherwise resembling the genus 

 Elasmopus; gnathopods rather like those of the genus Elasmopus, 

 the pahn of the second in the male undefined from the hindmargin 

 of article 6, bearing a stout process toward the finger hinge, finger 



