3i 



It seems to be very probable that arctica will prove to be identical with Verrill's 

 elegans, and with Leidy's falcidens \ possibly also with Zetesios. 



arctica 



28—30 



25 



1 1 — 12 



6-7 



15—16 



elegans ') 



25—30 



20 



9 — 1 2 



5—7 



12—15 



falcidens 



19 



? 



1 1 — 14 



6- 7 



18 



Zetesios (Bisc. Rept.) 



20 — 32 



25—33 



8—10 



7—9 



17—19 



Zetesios (Siboga Exp.) 



25—30 



20 — 26 



7—9 



8-9 



17—19 



That the first three are identical seems to be as certain as mere similarity of formulae 

 can make it; elegans would in this case take priority of arctica. Zetesios carries rather fewer 

 jaws and more anterior teeth, so that the probability of identity is not quite so great. In the 

 Synonymic List and Record of Distribution below, arctica and elegans stand as independent 

 species, and must remain so until a fuller description of the former is published, or until some 

 observer can compare specimens of the two. Falcidens has been placed under elegans in the tables. 



Sagitta bipunctata Quoy et Gaimard. 



J. R. C. Quoy et P. Gaimard. Observations zoologiques faites a bord de 1' Astrolabe en Mai 

 1826 dans le detroit de Gibraltar. Annales des Sciences Naturelles, Tome X, p. 1. 



Of some immature biptmctata lately received from the Zoological Station at Naples, the 

 two longest gave a formula of 8.5 : 23 : 8 : 4 — 5 : 9 — 1 1. Some well-developed specimens were also 

 obtained from the Laboratory at Plymouth. The only external difference noticeable between these 

 and the specimens from Parson's Bank (Biscayan Report, p. 69; and p. 17 above) lay in a slightly 

 greater extension backwards of the posterior fin ; it thus becomes about equally distributed on trunk 

 and tail, and falls into line with Grassi's figure of the species (op. cit., PI. I, fig. 4); in that case 

 the fully developed vesiculae seminales might swell to meet the posterior fins as in his drawina 

 (compare p. 5 above). The characters given in the Biscayan Report seem therefore to require 

 amendment in this point; the following should also have been added to the characters — "a short 

 and narrow thickening of the epidermis behind the head represents the rudiment of a collarette". 



The Neapolitan specimens of 8.5 mm. were at the same stage of sexual development 

 as Channel specimens of 19 mm., judged by the length of the ovary and the projection of the 

 vesiculae seminales. This may be connected with the early ripening of a warm-water race, but 

 is as likely to be due to the time of year at which the capture was made. 



Sagitta elegans Verrill. 



A. E. Verrill. Op. cit. 



F. S CONANT. Notes on the Chaetognaths. Johns Hopkins University Circulars. Vol. XV, p. 82. 



gracilis Verrill. 



A. E. VERRILL. Results of the explorations made by the steamer "Albatross". United States 



Commission of Fish and Fisheries. Part XI, p. 303 (For the year, 1883, published 1885). 

 falcidens Leidy. 

 J. Leidy. Op. cit. 

 ? arctica Aurivillius. 

 C. W. S. Aurivillius. Op. cit. 



1) From Conant's redescription. 



