224 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The animal was colorless and transparent, with a red eye-spot. It 

 was taken in a haul at Agar's Island. 



Acartia spinata n. sp. 



Plate 1, Figures 3, 5; Plate 2, Figures 16, 19; Plate 3, Figure 24; Plate 4, 

 Figures 37, 45. 



The forehead is smoothly rounded in each sex, as are the posterior 

 margins of the last thoracic segment ; these margins are provided, in 

 both the male and female, with heavy spines disposed in two sets (Plate 

 2, Figures 16, 19). The posterior borders of the abdominal segments and 

 likewise the furca are spinose on the dorsal side, and in the male (Fig- 

 ure 16) there are little spines on the sides of the second segment. The 

 length of the cephalothorax along the mid-dorsal line is 3^ times its 

 greatest width (Plate 1, Figure 3). The genital segment of the female 

 is about as long as the rest of the abdomen including the furca, and 

 the second and third abdominal segments are of about equal lengths. 

 In the male the genital segment is about one-third the length of the 

 second segment, which is twice the length of the third. Rostral fila- 

 ments are present (Plate 1, Figure 5). 



The anterior antennae reach back in the females to the end of the 

 anal segment, and in the males about to the posterior border of the 

 third thoracic segment. The second joint of the antenna in the female 

 (Plate 4, Figure 45) has a prominent spine on the ventral surface, and 

 the third joint has a similar spine on the anterior margin at the base 

 of the joint. That feature will distinguish this species from the other 

 species (bermudensis) described here. 



The fifth feet in each sex are of the usual form for the genus, but 

 exhibit specific characters. Those of the male are shown in Plate 3, 

 Figure 24 ; those of the female in Plate 4, Figure 37. 



The males average 1.13 mm. in length, the females 1.18 mm. 



The animals have a faint bluish tinge in the body when alive, while the 

 eye is very dark blue, this being a noticeable feature of the species. 

 These copepods are very abundant at North Rock and rather uncom- 

 mon elsewhere, though taken about Agar's Island. The species belongs 

 to the hifilosa-totisa-gieshrechti group, but differs from all the other 

 species in ways that are distinctive. 



Acartia bermudensis n. sp- 



Plate 1, Figure 1 ; Plate 2, Figures 10, 17, 18 ; Plate 3, Figure 22 ; Plate 4, 

 Figure 43. 



The females may be easily distinguished from those of the preceding 

 species by the absence of spines on the anterior antennae. Another 



