264 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



1 



a s a a a a a a a 



a d P. a cs os d 



20 minutes at each. The 35 remaining 

 specimens were taken from above 15 

 fathoms at the three remaining stations 

 by 20-minute tows. These facts in- 

 dicate that the species is typically 

 mesoplanktonicin the Philippine region, 

 which indication is supported by the 

 results of many other expeditions. In 

 the regions covered by the Biscayan, 

 Siboga, and Plankton expeditions, as 

 well as off the California coast, the 

 species occurs abundantly below 100 

 fathoms, but is rarely found above that 

 depth. It is common between 500 and 

 1,000 fathoms, and, as Ritter-Zahony 

 (1911, p. 62) says: "S. planktonis ist 

 unter alien Arten der Tiefsee am hau- 

 figste/i in der Literatur erwahnt." 



Genus PTEROSAGITTA Costa. 



Syn. Spadella LANGERHANS (part 1). 



PTEROSAGITTA DRACO (Krohn). 



Plate 36, figs. 11, 12, 13. 

 Sagitta draco KROHN (1853), p. 273. 

 Pterosagitta mediterranea COSTA (1869), p. 55. 

 Spadella draco FOWLER (1906), p. 25. 



MICHAEL (1911), p. 54. 

 Pterosagitta draco RITTER-ZAHONY (1911), 



p. 33. 



Thirty-two specimens were obtained, 

 of which only one has mature ovaries. 

 These completely fill the body cavity 

 (pi. 36, fig. 13), extending from tail- 

 septum to neck. All other specimens 

 are clearly immature, and in nearly 

 one-half there is no trace of ovaries, 

 and the seminal vesicles are barely 

 visible (pi. 36, fig. 12). Fowler (1906, 

 p. 26) records the tail as 41 to 57 per 

 cent of total length in specimens be- 

 tween 6 and 9 mm. The Philippine 

 specimens, however, vary only between 

 39.5 and 44.3 per cent. Otherwise 

 Fowler's records agree exceptionally 

 well with the Philippine material. 

 He records 7 to 9 seizing jaws, 7 to 



