CH^TOGNATHA. OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 987 



Sagitta planctonis (Steinhaus). 



Three specimens, taken at one station in the Antarctic Ocean, are probably to be 

 referred to this species. The tail-percentage and the numbers of the teeth and jaws 

 agree with those given by Ritter-Zahony, and the general habit — the stiff opaque 

 body — seems to be the same. A very characteristic feature of these specimens is the 

 size and arrangement of the anterior teeth : these are long towards the inner end and 

 considerably shorter towards the outer end of each row ; they do not overlap, but each 

 tooth is distinctly seen in every part ; these features are all admirably seen in a figure 

 given by Ritter-Zahony (1911). As the specimens are small and young, the collarette 

 is only slightly developed. 



Length. 



Tail- 

 percentage. 



Jaws. 



Ant. Teeth. 



Post. Teeth. 



12 



8 



25 



25 



9 

 10 



5 



4 



10 



8 



This species is given by Fowler (1906) as a tropical surface form, but it was 

 repeatedly taken in the Antarctic on the German South Polar Expedition, even as far 

 south as 66° S. (Ritter-Zahony, 191 1), so that its occurrence in the Scotia Antarctic 

 collections is not an isolated case. Its furthest south range is, however, extended by 

 about three degrees. 



Station : 280, 68° 40' S., 30° 18' W. Between surface and 500 fathoms. 



Temperature : 32-65° F. 



Pterosagitta draco (Krohn). 



Only a few specimens of this apparently common and typical tropical and sub- 

 tropical form were obtained at seven stations. This scarcity is probably due to the 

 fact that P. draco does not commonly occur at the very surface of the sea, but usually 

 at some little depth. This point would seem to be in agreement with the results of the 

 German South Polar Expedition (Ritter-Zahony, 1911), where this species was got 

 only twice in the surface tow-nets, whereas it frequently occurred in the vertical nets. 



Horizontal distribution : 26° 23' N., 20° 20' W.-38° 6' S., 14° 32' E. 



Vertical distribution : surface. 



Temperature range : 64'9°-78-6° F. 



Stations: 7, 11, 12, 14, 26, 56, 473. 



Euhrohnia hamata (Mobius). 



It might have been expected that this form would have been taken very frequently 

 in the higher latitudes, but, strange to say, it has been found in only six samples. The 

 specimens found were in every way typical. 



TRANS. ROY. SOC. EDIN., VOL. XLIX. PART IV. (NO. 18). 135 



