2o6 DISCOVERY REPORTS 



(h) Sagitta macrocephala 

 Sagitta tnacrocephala Fowler, 1905, The Biscayan Plankton of H. M.S. Research. Trans. Linn. Soc. London, Ser. 2, 



vol. X, p. 65. 

 S. macrocephala Fowler, 1906; Ritter-Zahony, 191 1, 1914; Germain & Joubin, 1916; Michael, 1919; Bollmann, 1934; 



Thiel, 1938; Tokioka, 1939; Fraser, 1952. 



An easily recognized species. The antarctic specimens appear to be identical with those from other 



oceans. 



Horizontal distribution. Widespread in all deep oceans, circumpolar, but always in small 



numbers. 



Table i. Comparison of the length and head armature of specimens of S. maxima at Stages III 

 and IV of maturity, from the Arctic, Antarctic and Peru Current 



(c) Eukrohnia hamata 

 Eiikrohnia hamata (Mobius), 1875. 

 E. hamata^ Ritter-Zahony, 1909, 191 1; Jameson, 1914; Johnston & Taylor, 1921; Burfield, 1930; Bollmann, 1934; 



Hardy & Gunther, 1936; Mackintosh, 1937; Thiel, 1938; Ghirardelli, 1953. 

 Spadella hamata Grassi, 1883; Fowler, 1896. 

 Krohnia foUacia Aida, 1897. 



K. hamata + K. hamata var. borealis Moltschanoff, 1907. 

 K. hamata Hertwig, 1880; Langerhans, 1880; Conant, 1896; Krumbach, 1903; Fowler, 1905, 1906. 



This well-known species exhibits a great deal of variation in size. In the Southern Ocean there are two 

 clearly defined races more or less separated by the antarctic convergence; and the specimens from 

 subtropical waters seem to belong to a smaller race also. E. hamata var. antarctica Johnston & Taylor 

 is the spent form which seems able to live for a while after spawning. 



Horizontal Distribution. Cosmopolitan in the deep oceans, circumpolar, maximum abundance 

 (in the Southern Ocean) in the vicinity of the antarctic convergence. 



{d) Heterokrohnia mirabilis 

 Heterokrohnia mirabilis Ritter-Zahony, 191 1, Revision der Chaetognathen. Deutsche Sudpolar Exped. Bd. xni (5), 



p. 42. 

 H. mirabilis Tchindonova, 1955. 



* Only those authors who have examined antarctic material have been included in the synonymy under E. hamata. 



