36 PROCEEDINGS OF THE NATIONAL MUSEUM vol.80 



detailed description of five copepodid stages in its life history. It is a 

 littoral form and is easily distinguished from the other species of the 



genus; 



DIOSACCUS TENUICORNIS (Claus) 



Dactylopus tenuicornis Claus, Die frei lebenden Copepoden, p. 127, pi. 16, figs. 



17-23, 1863. 

 Diosacciis temiicot-nis G. O. Saes, Cru.stacea of Norway, vol. 5, p. 146, pis. 89, 



90, 1906. 



Occurrence. — A single female was taken in the vertical net at 

 Station F on December 4, 1920, in water 16 meters deep over a 

 muddy bottom. This was the only specimen obtained during the 

 survey. 



Reinarhs. — Sars said that this species was abundant along the 

 whole Norwegian coast in the littoral zone among the algae. It is 

 probable, therefore, that it occurs in Chesapeake Bay in greater 

 abundance than this single capture indicates. It is not likely, how- 

 ever, to become of economic importance in the plankton of the bay. 



ECTINOSOMA CURTICORNE Boeck 



Ectinosoma ourticorne Boeck, Christiania Vidensk. Selskabet Foihaiidlinger, 

 p. 45, 1872.— G. O. Saks, Crustacea of Norway, vol. 5, p. 36, pi. 20, 1904. 



Occurrence. — ^Well distributed, more particularly in the inner bay, 

 where it was found at a majority of the stations. Taken usually 

 in the bottom net in the outer bay, but often at the surface in the 

 inner bay. A winter species but lasting into spring and sometimes 

 into summer. The largest single haul was in a vertical net at Sta- 

 tion Z on March 27, 1921, in 13 meters of water over a muddy bot- 

 tom, when about 700 specimens were obtained. 



Remarks. — This little copepod is found in sufficient numbers in 

 the inner bay to form an important constituent of the plankton. It 

 is evidently a littoral species and lives in brackish water. 



ECTINOSOMA NORMANI T. and A. Scott 



Ectinosoma normani T. and A. Scott, Trans. Linnaean Soc. London, vol. 6, p. 

 435, pi. 36, figs. 21, 29, 39 ; pi. 37, figs. 12, 26, 34, 51 ; pi. 38, figs. 5, 18, 42, 

 45 ; 1897.— G. O. Saks, Crustacea of Norway, vol. 5, p. 35, pi. 19, 1904. 



Occurrence. — About 30 specimens of this species, all females, were 

 taken in the bottom net at Station Y, January 27, 1921, from water 

 20 meters deep over a muddy bottom ; this is the only record for the 

 bay. 



Remarks. — This species is much less common than E. curticorne 

 and probably occurs but rarely in the bay. Like the other species 

 of the genus it is a littoral form and lives in the shallower and less 

 saline water. The bright-red pigment patch on each side of the 

 head between the bases of the first and second antennae forms a 



