242 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Altogether, these differences would seem to justify the description 

 of a new species, even though it may later prove to be synonymous 

 with S. decipiens. Had more than one individual been obtained, I 

 should feel certain of the validity of S. philippini, but as the matter 

 stands this single specimen might with as much justification be 

 regarded as an abnormal S. decipiens. 



SAGITTA ENFLATA Grassi. 



Plate 38, fig. 28. 



Sagitta enflata GRASSI (1883), p. 13. FOWLER (1906), p. 8. RITTER-ZAHONY 

 (1911), p. 13. MICHAEL (1911), p. 28. 



This species is represented in the Philippine collection by approxi- 

 mately 2,800 individuals. They usually exceed 20 mm. in length, 

 and the largest taken measures 31.5 mm. In the San Diego region, 

 on the other hand, the specimens rarely exceed 18 mm. in length, the 

 largest recorded (Michael (1911, p. 29)) measuring only 21 mm. 

 Again, the anterior teeth number 6 to 11, typically 7 or 8, in the 

 Philippine specimens, while they number 4 to 8, typically 6 or 7, in 

 San Diego specimens. Similarly, the posterior teeth number 9 to 15 

 in the Philippine specimens, the usual number being 14, while they 

 number 6 to 12 hi San Diego specimens, the usual number being 10 

 or 11. In all other respects, however, specimens from the two 

 localities are in agreement, and the Philippine specimens agree in 

 size and number of teeth with specimens described by Fowler (1906 

 p. 8) from the Siboga region. 



One puzzling fact is revealed by the Philippine collection. The 

 ovaries in most of the larger specimens are barely approaching 

 maturity, only one case of complete maturity having been discovered 

 in individuals exceeding 20 mm. in length; but among individuals 

 under 16 mm. in length many have mature ovaries (pi. 38, fig. 28). 

 In my San Diego report (1911, p. 56) a table is given of specimens of 

 S. enflata arranged in three groups according as their ovaries were 

 mature, approaching maturity, or remote from maturity. In the 

 first group the specimens varied in length between 12.5 and 19.5 mm., 

 in the second between 15 and 17.5 mm., and in the third between 8 

 and 15.5 mm. Obviously, these facts are open to two interpretations: 

 First, the ovaries hi San Diego specimens attain maturity only once 

 and that after a length of 12 mm. is reached; and, second, the ovaries 

 in the same individual become mature periodically, first when the 

 individual is not less than 12 mm. in length, and subsequently after 

 it has grown larger. If the second interpretation is eliminated, how 

 is the relation between length of individual and stage of maturity of 

 the ovary in the Philippine specimens to be accounted for ? It could, 

 of course, be readily explained on the assumption that two species 

 had been confused, but I am unable to discover any other differences 

 even remotely indicative of more than one species. In Table 1, for 



