i847- Campylonans Gray, A List of the Genera of recent Mollusca, their synonyms and types, 

 Proc. Zool. Soc. Lond., 1847, p. 149. 



1858. Euromus A. and li. Adams, The Genera of recent Mollusca, vol. II, p. 613. 



1876. Limacina (part.) Jeffreys, New and peculiar Mollusca of the family Eulimidae and other 

 families of Gastropoda, as vvell as of the Pteropoda procurcd in the "Valorous" 

 Expedition, Ann. and Mag. Nat. Hist. (4), vol. XIX, p. 337. 



I. Peraclis retictilata (d'Orbigny) var. minor n. v. (PI. I, fig. 4). 



Living animal: 



Stat. 243. 4°3o'.2S., 129° 25' E. 3 spec. 



Description; Shell almost entirely agreeing with the description, given by Pelseneer ^). 

 Four whorls, rapidly increasing, the last turn very large ; reticulation hexagonal, becoming less 

 marked towards the aperture, where it entirely disappears. The prolonged rostrum is bent forward. 

 Colour: Yellowish-red (spirit-specimen). 

 Dimensions: Height 1,25 mm.; max. diameter i mm. 

 O p e r c u 1 u m : Transparent, with six coils, rounded, left-handed. 



Animal: Head on a short proboscis, lips united ventrally; tentacles without sheath, and 

 symmetrical. Fins broad, truncated, without tentacular lobe, posterior lobe of the foot broad at the base. 

 It is only with hesitation that I can make up my mind to regard the specimens of the 

 Siboga-Expedition as a variety of the type. Comparing accurately the description and the 

 figures of Pelseneer with the foregoing, there may be found only the following differences : 

 I. The chief one is the difference in dimensions. Pelseneer notes: maximum length 4 mm.; 

 diameter 2,3 mm. The specimens of d'Orbigny ~) and those of Souleyet ^) which were 

 2 mm. high, have been regarded by Pelseneer as young individuals, though d'Orbigny 

 notes, notwithstanding the small size, four whorls in the spiral, and moreover that the 

 reticulation is often not seen towards the aperture. 

 II. The operculum has six coils, not four. It corresponds entirely with Boas' figure ^), if this 

 be regarded as seen from the inside. 



III. The apex is more obtuse than in Pelseneer's figure, the first turn being almost in the 

 same plane as the second. 



IV. The inner lip of the aperture is very thin. 



Though readily consenting that the differences from the type are very insignificant, I 

 do not believe that the Siboga-specimens are quite identical with it. Particular attention must 

 be paid to the genus Peraclis^ being the most important among the Thecosomata. 



2. Peraclis rissoides n. sp. (PI. I, figs 5, 6, 11, 13, 14). 



Living animal: 



Stat. 243. 4°3o'.2S., 129° 25' E. i spec. 



Description: .Shell as in Peraclis reticiilata var. minor ^ that is to say : apex obtuse, 



1) Challenger Rep. LXV, p. 34, pi. I, figs. 7 — 8. 



2) Voyage dans l'Amérique meridionale, vol. V, p. 178. 



3) Voyage de la Bonite, vol. II, p. 220. PI. 13, figs 17 — 19. 



4) Spolia atlantica. PI. III, fig. Sgl"'s. 



