CHAETOGNATHA. 



WITH A NOTE ON THOSE f'OLLE<TKl> BY H.M.S. 'CHALLENGER 1 IN 

 SITBANTARCTIC AND ANTARCTIC' WATKRS. 



BY G. HKKBKRT FUWLRR, B.A., PH.D., F.LS. 

 (1 Chart.) 



I. THE COLLECTION OF THE ' DISCOVERY.' 



THR specimens mentioned l>elow include all those taken south of 40 S., a parallel 

 selected to include what appear to l>e the critical temperatures which separate a 

 temperate and subantarctic plankton from truly Antarctic forms. The material was 

 preserved in alcohol, and was mostly in fair condition, hut presented the usual 

 disadvantages which attend upon the use of this reagent for Chaetognatlm. 



Only three species were represented. The tables of formula},* given under each 

 species, serve to show the relation between the more obvious variations which occur in 

 these southern specimens and those in specimens from other localities. In these tables 

 the first column of figures gives the total length in millimetres (including the tail fin) ; 

 the second, the length of the tail expressed as a (tcrccntagc of the total length ; the 

 third, the numlicr of jaws ; the fourth, the numlicr of anterior teeth (or of the only row 

 of teeth in the case of KroluiHt) ; the fifth (when present), the number of posterior 

 teeth. 



SAGITTA HRXAPTRRA. 



Sajitta fiffajitrra, D'Orhignr, Voyage dans I'Amcriquc meridionalc. Tome V., :;"" partie ; Mollug<{ti<*, 

 p. 148. (18S5-1K43.) 



The species was represented by numerous specimens. They agreed with typical 

 hetaptera in almost every one of such diagnostic features as they had retained, the 

 exceptions being that the anterior fin appeared to extend slightly further forward than 

 is usually the case (due possibly to imperfect pieservation), and that the first (newest) 

 jaw hardly showed the usual ridge and bay just below the tip ; the extent to which 



* The latent papers on Chaetognatha, iimmriing the distribution and literature of the group, are : " Biscayan 

 Plankton collected daring a cruise of H.M.S ' Reaearch,' 1000, Part III. The Chaetognatha " ; Transaction* of 

 the Linruran Society. 2nd Series, Zool., Vol. X., pp. 65-87 ; and " Reports of the Siboga ' Expedition. Mono- 

 graph XXI., The Chaetognatha " (Leiden, 1908). 



VOL. 111. Y 



