266 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



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Genus EUKROHNIA Ritter-Zfihony. 



Syn. Krohnia LANGERHANS (part). 



EUKROHNIA HAMATA (MSbius). 



Plate 37, figs. 14,27. 



Sagitta hamata MOBIUS (1875), p. 158. 



Krohnia hamata KRUMBACH (1903), p. 639. FOW- 

 LER (1905), p. 74; (1906), p. 23. 



Eukrohnia hamata RITTER-ZAHONY (1911), p. 39. 

 MICHAEL (1911), p. 51. 



This species is represented by six poorly 

 preserved and badly damaged specimens (Cat. 

 No. 17928, U.S.N.M.). The heads of all but 

 two are missing and in one of those it is 

 torn away from the body. It is impossible, 

 therefore, to accurately determine the length 

 or to count the teeth and seizing jaws in 

 four of the six specimens. The other two 

 are 16 and 16.3 mm. in length; their tails 

 are 28.3 and 30.2 per cent of their lengths; 

 the number of teeth are 21-21 and 24-25, 

 and the number of seizing jaws are 9-10 

 and 9-9. 



The number of teeth (pi. 37, fig. 14) greatly 

 exceed that recorded by Ritter-Zahony 

 (1911, p. 39) for specimens taken from the 

 Antarctic Ocean, as well as that recorded 

 by me (1911, p. 52) for specimens from the 

 San Diego region. Although Ritter-Zahony 

 records a variation in number of teeth from 

 4 to 23, he gives 12 as the upper limit for 

 specimens under 18 mm. in length. Simi- 

 larly, in specimens from the San Diego region 

 between 13 and 17.5 mm. in length, I have 

 never found more than 13 teeth. Fowler 

 (1906, p. 23), however, records 22 in speci- 

 mens from the Siboga area that are only 13 

 mm. hi length. It is evident, therefore, 

 that the number of teeth vary according 

 to the region in which the species occurs. 



The pouits of the seizing jaws (pi. 37, fig. 

 27) are curved to an unusual extent, and 

 the jaws are not serrated as described by 

 Krumbach (1903). Otherwise, however, the 

 structure of the jaws agree with his de- 

 scription. 



