6 PROCEEDINGS OF THE NATIONAL MUSEUM vol.82 



Remarks. — Nordquist (1888), de Guerne and Kichard (1889), and 

 Schacht (1898) considered that there is not sufficient difference to 

 warrant the adoption of another specific name. It is a fact, however, 

 that the differences as given above exist, and it is probably best to 

 recognize them by a specific name. 



This species was originally described from material collected in 

 the Gulf of Finland. It has been found in many parts of the eastern 

 Baltic as well as the Gulf of Finland and the Gulf of Bothnia, on 

 Kolguev Island in the Kara Sea, at the mouth of the Jana, in the 

 sea off Spitsbergen, and in Greenland. Sars found it in the Caspian 

 Sea and in 1897 gave a detailed description of it. Willey (1920) 

 reported it from Collinson Point, Alaska; this collection was made 

 by Frits Johansen in the Arctic Ocean, about 100 yards from shore 

 in about 1 fathom of water. L. johanseni was collected inland from 

 that point in a pond about 4 feet deep ; this pond apparently had no 

 connection with the ocean, and the location where L. grimaldii was 

 collected was not connected in any way with fresh water. Willey 

 (1923) reported finding L. griimaldii in large numbers in the stomach 

 contents of the capelin {Mallotus villosus). 



Sars (1898) stated that the specimens from the mouth of the Jana 

 were much larger than those from the Caspian, and expressed his 

 belief that Z. grimaldii is a more Arctic form and that its presence 

 in the Baltic and Caspian Seas is evidence of a former connection of 

 those basins with the Arctic. Its occurrence at the mouth of the 

 Jana, in the Kara Sea, at Kolguev Island, Spitsbergen, Greenland, 

 and Collinson Point would indicate a wide distribution in the Arctic. 



The size of the male, as given by different authors, is 2 to 2.5 mm; 

 of the female, 2.8 to 3.6 mm. 



The segmentation regeneration of the terminal part of the right 

 antenna of the male is discussed under the description of the genus. 



LIMNOCALANUS JOHANSENI Marsh 



Plate 1, Figures 1, 8, 9 ; Plate 3, Figures 4-7 ; Plate 13, Figure 6 

 Limnocalanus johanseni Marsh, 1920, pp. 3j-4j, pi. 1, figs. 1-8. 



The head, as shown in Plate 1, Figure 1, is not vaulted as in L. 

 mMcrurus. The front is armed with two projections. The last 

 cephalothoracic segment is rounded on the sides and each side is 

 armed with a small spine, which may be sharp, as in Plate 3, Figure 

 5, or blunt, as in Plate 3, Figure 6. 



In the abdomen of the female (pi. 13, fig. 6) the first segment is 

 somewhat expanded laterally and is about twice as long as the sec- 

 ond: the third segment is slightlv longer than the second. The 



