28 THE VOYAGE OF H.M.S. CHALLENGER. 



*2. Pneumonoderma violaceum, d'Orbigny (PI. I. fig. 9). 



1815. Pneumoderrnis atlantica, Oken, Lehrbuch der Zoologie, Bd. i. p. 327. 



1832. Pneumodermon peronii, Quoy and Gairnard, Voyage de decouvertes de r Astrolabe, 



Zoologie, t. ii. p. 388, pi. xxviii. figs. 1-6. 

 1840. Pneumodermon violaceum, d'Orbigny, Voyage dans lAme>kpue meridionale, t. v., pi. ix. 



figs. 10-15. 

 1850. Pneumodermon cucutlatum, Gray, Catalogue of the Mollusca in the Collection of the 



British Museum, p. 39. 

 1852. Pneumodermon peronii, Souleyet (jmis), Voyage de la Bonite, Zoologie, t. ii. p. 274, 



pi. xiv. figs. 12, 15. 

 1852. Pneumodermon audebardi, Bang, Histoire naturelle des Mollusques Pt6ropodes, pi. x. 



fig. 13. 

 1859. Spongiobranchea australis, Chenu (pars), Manuel de Conchyliologie, t. i. p. 116, fig. 508. 

 1879. Cirrifer paradoxus, Pfeffer, Uebersicht der auf S. M. Schiff " Gazelle " und von Dr. Jagor 



gesammelten Pteropoden, Monatsber. d. k. preuss. Akad. d. Wiss. 

 Berlin, p. 249, fig. 20. 



Body and head resembling those of Pneumonoderma mediterraneum. 



Foot. — Posterior lobe not so long as in the foregoing species. 



Lateral Gill short ; lateral somatic crests without fringes. 



Posterior Gill with long radiating crests, each of which bears about seven ramified 

 fringes on each side of the base. 



Acetabidiferous Appendages triangular in shape, of moderate length, and rather large 

 at their base. Each appendage bears about forty suckers covering their whole median 

 face ; these suckers are smaller than those of Pneumonoderma mediterraneum, but have 

 nearly the same shape. 



Colour. — Brownish ; the pigment being chiefly distributed on the right side. I have 

 seen specimens in the Hamburg Museum which are nearly colourless, or albinos, and 

 have but very little pigment on the right side of the head. 



Length. — About 13 mm. Souleyet 1 gives the length of the Atlantic Pneumonoderma 

 that he studied (and which belongs to the present species), as 25 mm.; but this is 

 certainly with the proboscis and hook-sacs everted. 



Challenger Specimens. — Near Station 354, May 7, 1876; Atlantic, off the Azores; 

 lat. 34° 22' N., long. 34° 23' W. 



In the Narrative of the Cruise (vol. i. p. 219), there is also mentioned a "Pneumo- 

 dermon " (without indication of species) collected between Cape Verde and Bahia, 

 Stations 93 to 128, July 27 to September 14, 1875. 2 I did not, however, find, in the 

 collections sent to me, any specimens of Pneumonoderma from any station between the 



1 Voyage de la Bonite, Zoologie, t. ii. p. 274. 



2 In this trip there were only four trawlings (Stations 101, 104, 106 and 107, from St. Vincent to St. Paul's Rocks), 

 between lat. 5° 48' N. and lat. 1° 22' N., and from long. 14° 20' W. to long. 26° 36' W.; this zone quite agrees with 

 the area of distribution of Pneumonoderma violaceum. 



