298 Transactions of the Society. 



inner edge. Third joint (inner spine) long and stout, with a 

 similar membrane. 



Measurements (averages) : — 



Sagittal 



,, with furca 

 Thorax 

 Abdomen, total 



,, 1st segment 



2nd „ 



ii 3rd 



4th 



„ 5th 



Furca 



Left antenna 



This species was found in considerable numbers in pools at 

 Oued Tindja near Tunis. It is of a bright blue colour, the colour 

 persisting in some preserved specimens but fading in others. 



Diaptomus chevrcuxi Guerne and Eichard. — The specimens de- 

 scribed under this name by Guerne and Eichard were found in the 

 high plateau region on the road from Algiers to Laghouat. I found 

 it to be common in ponds at Biskra, but it did not occur in any of 

 my collections in the coastal, or Tell region. 



Diaptomus wierzejskii Eichard. — This species appears to be 

 common and widely distributed in Algeria and Tunisia. It was 

 common at Biskra, and also at Sidi Athman and Oued Tindja, near 

 Tunis. 



Diaptomus salinus Daday. — This species was found only in 

 Lake Sedjouma, by Tunis, and in salt pools by the shore of the lake. 

 These pools had a density of 1*013-1 -017. 



In one male specimen a slight, but rather curious, abnormality 

 was noticed. The first joint of the exopodite of the left fifth foot 

 bears a peculiar stout spine with a basal branch and a terminal 

 cluster of teeth. This joint does not, as a rule, bear either a spine 

 or a seta (plate XIV. fig. 40). 



Diaptomus ingens sp. n. — Female : Body robust, the greatest 

 width falling in the first segment of the thorax. Last segment 



EXPLANATION OF PLATE XIV. 



Fig. 39. — Diaptomus cyaneus. Terminal joints of right antenna of male, x 260. 

 ,, 40. — Diaptomus salinus Dad. Abnormal left 5th foot of male, x 260. 

 ,, 41. — Diaptomus ingens sp. n. Terminal joints of right antenna of male, x 98. 

 ,, 42. — Ditto. Abdomen of male, x 37. 

 ,, 43.— Ditto. 5th leg of female, x 70. 

 ,, 44. — Ditto. 5th leg of male, x 98. 

 ,, 45. — Ditto. Abdomen of male, x 57. 



,, 46. — Poppella gucrnei Rich. Margin of the 24th joint of the antenna of the 

 female, x 1050. 



