NOTES ON A NEW SPECIES OF GYMNOPLEA. 101 



(1) Abdomen of female two-jointed instead of tliree. 



(2) Antenna 1, male, left, twenty-six joints ; female, both 

 twenty-six instead of twenty-five. 



(3) Mandible : Exopodite consists of one joint instead of five. 



(4) Maxilla 2 : Basipodite not obviously jointed, as in 

 Diaptomus; proximal and distal seta3 equal in leng-th instead 

 of unequal. 



(5) Thoracic 5, male, riyht, endopodite consists of three 

 joints instead of one Left, exopodite one-jointed, two 

 cushions with smooth surfaces, and no "appendage." (In 

 Diaptomus, exopodite two joints, the two cushions having a 

 fringe of fine spines, and an " appendage" is present.) 

 Endopodite not found, but described in Diaptomus. Female, 

 third joint of exopodite absent, being replaced by a spine (s.) 

 (a small third joint present in Diaptomus). 



This species agrees with Paradiaptomus in : 



(1) Abdomen of female two- jointed. 



(2) Maxilliped : Endopodite three-jointed instead of five, 

 as in Diaptomus. 



(3) Thoracic five, male, left, '"no appendage" on the outer 

 side of end joint of exopodite, present in Diaptonms. 



Chakacter Peculiar to Present Species. 



Antenna 1 : Left of male, and right and left of female, 

 twenty-six joints. This very peculiar character appears to be 

 due to the division of the second joint. In the great majority 

 of the Gymnoplea this second joint is longer than the third, 

 fourth, etc., while in the new species the difference in size is 

 not observable, and the position of the spine (6-2), fig. 5, at the 

 proximal end instead of in the middle of the third joint, 

 favours this view — that the additional joint is ob-tained by 

 the division of the second joint of a typical antenna. The 

 hypothesis is supported both by the size of the second joint 

 and the position of the spine in Diaptomus orientalis (see 

 fig. oa, 5.2). 



It appears impossible, with these differences, to place this 



