FEESH-WATER CYCLOPlDiE AND CALANID.E. 37 



Male. — The right (geniculating) anterior antennae is twenty- 

 two- jointed, the antepenultimate joint bearing a large serrated 

 lateral appendage, which reaches as far as the middle of the fol- 

 lowing joint, the number of serratures varying from seven to 

 about twelve. Left antenna twenty -five -jointed, and reaching 

 nearly to the extremity of the abdomen. Inner branch of the 

 right fifth foot of moderate size, simple, one-jointed, truncated 

 at the apex, and reaching as far as the apex of the second joint 

 of the outer branch: first joint of the outer branch produced 

 externally into a large acuminate process : terminal claw long, 

 slender, somewhat flexuous or subsigmoid, and having part of 

 the margin very finely (almost imperceptibly) pectinated. Inner 

 branch of the fifth foot of the left side very small ; outer branch 

 about twice as long, slender, and terminating in two very slender, 

 subequal, and very finely pectinated setae. The second joint of 

 the protopodite of the right fifth foot possesses a curious marginal 

 hyaline lamina, communicating, apparently, with the interior of 

 the organ ; and the same joint of the left limb has a similar struc- 

 ture of an elongated pyriform shape. Length of the male, 1*6 

 mm.; female, 1*75 mm. 



The description here given differs in some important particu- 

 lars from that of Prof. Lilljeborg. The anterior antennae in the 

 Scottish specimens have, in the female, on both sides 25 joints, 

 whereas Lilljeborg states the number of joints at 23 : in the 

 male the right attennae has 22, the left 25 joints ; the Russian 

 specimens having respectively 23 and 24 joints. Again, in the 

 male fifth foot of the left side I am unable to find the ciliated 

 nodule described by Lilljeborg, while in the same organ of the 

 female I find the inner branch to be composed of a single joint — 

 not of two, as stated by Lilljeborg : he, however, adds that in 

 imperfectly developed specimens there is only one joint. But 

 notwithstanding these discrepancies I think there can be no 

 doubt that the species referred to are the same. 



D. serricomis was taken by Mr. T. Scott, F.L.S., of the Scot- 

 tish Fishery Board, in Loch Mulloch Corrie, Sutherlandshire, 

 where it occurred in considerable numbers. To his kindness I 

 am indebted for specimens, and for the opportunity of describing 



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