10 Gr. 0. Sars. 



genus Estheria, but differing in several points rather markedly, 

 both as to the shell and the enclosed animal, and forming-, 

 as it were, a transition to the Limnadia group. Besides 

 the South African species described below, the following, 

 5 species may with certainty be adduced to this genus: 

 Estheria dahalensis, Rüppel, E. ticinensis, Crivelli, E. com- 

 pleximana, Packard, E. Macgillivrayi, Baird and E. Ru- 

 bidgei, Baird, the last 2 likewise belonging to the South 

 African fauna, but hitherto only described from empty 

 shells. The most prominent generic character, which how- 

 ever seems to have escaped the attention of earlier authors, 

 is undoubtedly the peculiar transformation of the upper 

 lappets of the exopodites in the 10th and 11th pairs of 

 branchial legs in the female to sausage-like appendages 

 somewhat resembling those found in the genus Limnetis. 

 In no other true Limnadiid has such a transformation been 

 observed. The apparently movable spine appended to the 

 tip of the rostral projection has been noted by Grube in 

 L. dahalensis and ticinensis, and in all probability it will be 

 found to occur in all the species of the present genus. The 

 peculiar securiform plate, too, issuing inside from the lower 

 lappet of the exopodite, has likewise been observed by 

 Grube in the 2 above-named species, and the figures he 

 gives of the caudal piece in L. ticinensis also agrees in all 

 essential points with that in the South African species. 

 As to the North American species Estheria compleximana, 

 Packard, the representation of the male given by that 

 author undoubtedly stamps it as a genuine species of the 

 present genus, and the complicated structure of the 2 an- 

 terior pairs of legs, from which the specific name has been 

 derived, agrees very nearly with that found in the male of 

 the South African species. 



