REPORT ON THE PTEROPODA. 29 



two above cited. But since all the stations between these latter are north of lat. 15° S., 

 the specimens noticed undoubtedly belong to Pneumonoderma violaceum. 



Habitat. — This species lives only in the Atlantic Ocean, and especially in that part 

 adjoining the African coast, and is distributed between lat. 45° N. and lat. 15° S., the 

 extreme western localities (long. 45° W.) are in the northern hemisphere, the most 

 eastern (long. 6° W.) in the southern hemisphere. 



Observations. — Boas, 1 with some doubt, ascribes to the present species specimens from 

 the Indian Ocean, but they are certainly distinct, because each of their buccal appendages 

 only bears from twenty-five to thirty suckers. 



In this species Boas 2 also includes specimens from the south-east Pacific (off Caldera, 

 Chili), but they are the types of a new species, Pneumonoderma boasi, described 

 further on. 



# 3. Pneumonoderma peroni, Lamarck (PL II. fig. 2). 



1815. sEgle cucullata, Oken, Lelirbuch der Zoologie, Bd. i. p. 327. 



1819. Pneumodermon peronii, Lamarck, Histoire naturelle des Animaux sans Vertebres, t. vi. 



p. 294. 



Body. — Head and foot as in the foregoing species. 



Lateral Gill short, with fringed lateral somatic crests. 



Posterior Gill with long radiating crests, each of which bears, on each side of the 

 base, as many as twelve contiguous fringes, very much developed and subdivided. 



Acetabuliferous Appendages triangular, with a large base, bearing about a hundred 

 suckers a little smaller than those of Pneumonoderma violaceum, more convex and 

 inserted on very extensible peduncles. 



Radida. — In the largest specimens I was able to examine (about 15 mm.), the 

 formula was 4:0:4. 



Colour. — Bluish-grey ; pigment divided into numerous little spots, visible under a 

 magnifying glass. 



Length. — A little greater than that of Pneumonoderma violaceum; the adult 

 specimens measure 15 mm. 



Cliallenger Specimens. — Station 222, March 16, 1875; off the Admiralty Islands; 

 lat. 2° 15' N., long. 146° 16' E. 



Habitat. — Indian Ocean, "from the equator to lat. 40° S., and the seas of the Malay 

 Archipelago ; this species also lives in the south Atlantic Ocean, but only south of the 

 Tropic of Capricorn, while Pneumonoderma violaceum is only to be found north of this 

 tropic and has its southern limit at lat. 15° S. ; Pneumonoderma peroni, on the contrary, 

 is only to be found from lat. 25° S. to lat. 37° S., and between long. 0° and 34° W. 



1 Spolia atlantica, p. 154, Nos. 42 and 43. 2 Spolia atlantica, p. 154. 



