992 DR. G. HERBERT FOWLER OX THE [Dec. 15, 



BIOLOGY 



the methods employed and the general questions of distribution 

 will be left to the last paper. 



SAGITTA WHAETOISTI, sp. n. 1 (Plate L. figs. 1-3.) 

 Tn external form this species resembles most nearly $. lyra 

 (Krohn), and differs from all other species yet described in the 

 approximation, almost fusion, of the paired lateral fins. Prom 

 Krohn's species, however, it is easily distinguished by the absence 

 of a constriction between body and trunk and by the numbers of 

 the teeth and cirrhi. 



The head is large, 3-4 mm. wide and 2 mm. long in a specimen 

 45 mm. long. It bears on each side 8-10 stout cirrhi (Greifhaken), 

 which are strongly curved, and of which the middle three are the 

 longest. The accessory teeth (Nebenkiefer) are arranged in two 

 series, of which the more dorsal are 3-5 in number and are short 

 and stout ; the more ventral are 5-7 in number and are slighter 

 and longer. The neck is somewhat thinner than the body. The 

 body tapers without constriction to the tail ; the latter (post-septal 

 region) is less than one-fourth of the total length. The lateral 

 fins are set rather far back, the anterior being much longer and 

 narrower than the posterior. 



The longest specimen measured 45 mm. The following dimen- 

 sions are taken from well-preserved straight specimens, of which 

 A was apparently uncontracted, B contracted considerably antero- 

 posteriorly : 



A. B. 



Total length .. 30 mm. 38 mm. 



Head, 1 2 



Body, 23 26 



Tail, 6 10 



Neck, width 1-5 3 



Body, width at widest .... 2 4 



Anterior fin, length 20 18 



width 3 6 



Posterior fin, length 10 7 



width 4 9 



Tail-fin, width 3 6 



It is curious that this species should not have been taken by the 

 Plankton Expedition, which records 2 S. Upunctata from the north 

 of Scotland. From this it is distinguished readily by the approxi- 

 mation (continuity) of the lateral fins. 



Prom S. hexaptera it is further distinguished by the size of the 

 head, by the slightly more backward position of the posterior 

 lateral fin, by the possession of more numerous cirrhi, and by the 

 absence of the five-rayed star on the accessory teeth (cf. Strodtmann, 

 loc. cit.). 



1 In honour of Admiral Wharton, E.N., the Hydrographer, a steady friend 

 to oceanic research. 



2 Strodtmann, "Systematik der Chaetognathen," Arch, fur Naturgeschichte, 

 hiii. Band i. pp. 333-376, pi. xvii. 



