254 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



SAGITTA DECIPIENS Fowler. 



Plate 35, fig. 8; plate 37, figs. 18, 22. 



Sagitta decipiens Fowler (1905), p. 70. — Ritter-Zahony (1911), p. 27. 

 Sagitta sibogae Fowler (1906), p. 21.— Ritter-Zahony (1909a), p. 5. — Michael 

 (1911), p. 74. 



According to Ritter-Zahony (1911, p. 29), there is "keine spezi- 

 fischen Unterschiede in Fowler's Diagnosen und Abbildungen der 

 beiden Arten [S. decipiens und S. sibogae] und S. sibogae weist 

 danach — als alteres Stadium ! — gegeniiber S. decipiens eigentlich nur 

 bedeutendre Dimensionen und hohere Zahlen fur die Vorder- und 

 Hinterzahne auf. " 



Although the species is represented in the Philippine collection 

 by more than 100 specimens, few are well enough preserved to permit 

 accurate measurements and their identification is therefore not 

 certain. They have more anterior and posterior teeth than recorded 

 by Fowler (1905, p. 70) in his original description, 8 to 11 anterior 

 and 19 to 22 posterior teeth against his records of 5 to 10 anterior and 

 12 to 18 posterior teeth. They agree, however, with his (1906, p. 21) 

 records for S. sibogae, in which the anterior teeth number 7 to 10 and 

 the posterior teeth 13 to 23. They also agree, not so well perhaps, 

 with Ritter-Zahony 's (1911, p. 28) records. He gives the number 

 of anterior teeth as 7 to 9 and the number of posterior teeth as 12 to 

 20. The species is redescribed on the basis of the Philippine material. 



Collarette (pi. 35, fig. 8) inconspicuous, varying in length from 

 slightly less than one-quarter to slightly more than half the body 

 width. Body flabby, seldom retaining its form well, and widest on 

 level with posterior end of anterior fins, tapering gradually toward 

 head and tail. No constriction at tail-septum. Ovary short, not 

 extending beyond anterior limit of posterior fins. Corona ciliata 

 not observed. 



Anterior fins (pi. 35, fig. 8) rayless throughout anterior half, 

 longer and narrower than posterior fins, and extending slightly 

 beyond posterior end of ventral ganglion. Interval from anterior 

 to posterior fins about equal to maximum width of body. 



Posterior fins (pi. 35, fig. 8) rayless in anterior extremity. They 

 never extend posteriorly to seminal vesicles, the interval varying in 

 length from about 25 to 110 per cent of the maximum body width. 

 More than 50 per cent of fin in front of tail-septum, varying from 54 

 to 65 per cent. Form irregular, the position of greatest width being 

 at or just behind tail-septum. 



Vestibular ridge (pi. 37, fig. 18) concealed by a thick cuticle. It 

 is characterized by large fairly regular papillae extending internally 

 beyond the teeth and terminating near the mo\ith. Wing covers 

 all except the first one or two teeth, the notch extending to the 

 third 6r fourth. External process not observed. According to 



