260 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Anterior teeth 5 to 9 in number. They are closely set, provided 

 with broad bases, and diverging distally. 



Posterior teeth (pi. 37, fig. 21) 10 to 14 in number. They are long, 

 broad, closely set, and diverging distally. 



Seizing jaws (pi. 37, fig. 25) 4 to 6 in number. Point with an 

 oval base inserted into shaft between 15 and 20 per cent of its height. 

 Base of point and top of shaft converge toward back of shaft. Edge 

 of shaft provided with narrow crest. Pulp-canal central, and extend- 

 ing into point about 80 per cent of its height. Pulp evenly dis- 

 tributed throughout canal. 



Table 14. — Measurements of Sagittaferox. 1 



i All measurements made in per cent of total length of animal. 



s Per cent of posterior fin in front of tail-septum. 



8 The + indicates that the fin extends beyond posterior end of ganglion. 



* The + indicates that the collarette extends beyond anterior end of ganglion. 



Distribution. — S. ferox was collected from 22 of the 46 stations 

 from which chaetognaths were taken, 598 specimens being obtained. 

 It is difficult to decide whether the species is typically epiplanktonic 

 or mesoplanktonic in the Philippine region. At 15 stations it was 

 taken from above 100 fathoms. Five, or 33 per cent of the epiplank- 

 tonic hauls, and two, or 29 per cent of the mesoplanktonic hauls, 

 obtained more than the average number of specimens (27). Again, 

 the median number of those taken above 100 fathoms is nine, but 

 nine is also the median number of those taken below 100 fathoms. 

 Finally, the greatest number was taken from 25 fathoms, the second, 

 fhird, and fourth greatest from the surface, and the fifth greatest 

 trom 500 fathoms. 



All subsurface hauls, however, were made by various types of open 

 nets. It is well to remember that such hauls, whether horizontal or 

 vertical, afford no certain evidence of the depth from which specimens 



