1911] Michael: Ckaetognatha of the San Diego Region. 69 



Sagitta elegans Verrill 



PI. 2, figs. 12, 13; pi. 3, fig. 24; pi. 4, fig. 38. 



Sagitta elegans Verrill (1873), p. 332; Conant (1896), p. 84. 



Sagitta arctica Aurivillius (1896), p. 188. 



Sagitta gracilis, Verrill (1883) [see Conant (1896), p. 84]. 



Sagitta bipunctata, Krumbach (1903), p. 628. 



Sagitta biptinctata forma arctica, Eitter-Zahony (1910), p. 256. 



Through the courtesy of the United States National Museum 

 I have been enabled to study a few specimens of Verrill's (S. 

 elegans. The specimens were originally obtained from Vineyard 

 Sound, Massachusetts. From Dr. Hjalmar Broch, of Christiania, 

 Norway, I have also some specimens of 8. arctica, obtained 

 November 16, 1905, from the Skagerak. Fowler (1906) pointed 

 out that these two forms were probably to be identified as a 

 single species, and later Ritter-Zahony (1910) synonymized 

 them with S. hipunctata. It is, therefore, advisable to redescribe 

 them and inasmuch as they are so nearly alike (pi. 2, figs. 12, 13), 

 I shall describe S. elegans and then briefly consider the main 

 points in which it differs from S. arctica. 



Characters 



Body opaque (pi. 2, fig. 12), but rather flabby. Neck well marked, but 

 scarcely so pronounced as in S. enflata or S. hexaptera. Body widest 

 throughout posterior third, tapering gradually toward head and more 

 rapidly toward tail. Lateral fields conspicuous but not large. Muscles 

 strong and thick. Diminution at tail-septum rather abrupt. Collarette 

 absent. 



Anterior fin situated well forward, shorter and narrower than posterior 

 fin. It does not extend to the ventral ganglion, the interval measuring 

 about 6 per cent. Approximately triangular in form, the point of greatest 

 width being located well toward its posterior end. Interval from anterior 

 to posterior fin about 12 per cent. 



Posterior fin extends nearly, if not quite, to seminal vesicles. Always 

 more than 50 per cent of fin in front of tail-septum, and usually more 

 than 60 per cent. Position of greatest width slightly behind tail-septum. 



Vestibular ridge (pi. 3, fig. 24) provided with low, rounded papillae 

 which are rather irregular in height and position. They are not so 

 numerous as the posterior teeth. Four or five teeth usually project beyond 

 wing of ridge. The external process could not be discerned. 



Anterior teeth 6 to 11. Posterior teeth 13 to 17. 



Seising jaws (pi. 4 fig. 38) 9 to 12 in number, and of much the same 

 form as described by Krumbach (1903) for S. bipunctata. Points needle- 

 shaped but with the apex lying slightly nearer edge of jaw. Base of point 



