276 



TIIE VOYAGE OF H.M.S. CHALLENGER. 



but rising in broad shallow steps. Apex small, raised. Whorls 5, flattened or even 

 slightly concave above, strongly keeled and angulated in the middle, of regular increase ; 

 the last is very large and ventricose, with an elongated but convex base, and a very small 

 snout. Suture impressed, very horizontal. Mouth fully half the size of the shell, oval, 

 angulated at the keel and at the base of the pillar. Outer lip rounded and open, 

 advancing a little in front of the point of the pillar. Inner lip thinly spread on the 

 body, with a small chink in front behind the pillar, the edge of which is narrow and 

 twisted, with two indistinct folds above it. H. 0"4 in. B. - 28. Penultimate whorl, height 

 0-07. Mouth, height 0-3, breadth 0'17. 



I failed to extract tlie animal from the shell ; but plainly it had no operculum, 

 bluntness and tabulation of the spire give a very peculiar aspect to this species. 



The extreme 



Family Pleukotomacea, 1 Loven, 1847. 

 Genera. 1. Pleurotoma," Lam. 2. Clathurella, Carp. 3. Borsonia, Bellardi. 4. Clionella, Gray. 



1. Pleurotoma, 3 Lamarck, 1799. 



Species. 



1. Pleurotoma marmorata, Lam. 14. 



2. Pleurotoma monilifera, Pease. 15. 



3. Pleurotoma speciosa, Reeve. 16. 



4. Pleurotoma tigrina, Lam. 17. 



5. Pleurotoma undosa, Lam. 18. 



6. Pleurotoma ischna, Wats. 19. 



7. Pleurotoma spicea, Wats. 20. 



8. Pleurotoma xanthophaes, Wats. 21. 



9. Pleurotoma phymatias,'Wats. 22. 



10. Pleurotoma (Surcula) brevicaudata, Reeve. 23. 



11. Pleurotoma (Surcida) deshaysii, Doumet. 24. 



12. Pleurotoma (Surcula) leucotropis, Ad. and 25. 



Reeve. 26. 



13. Pleurotoma (Surcula) oxytropis, Sow. 27. 



Pleurotoma (Surcula) tuberculata, Gray. 

 Pleurotoma (Surcula) staminea, Wats. 

 Pleurotoma (Surcula) trilix, Wats. 

 Pleurotoma (Surcula) lepta, Wats. 

 Pleurotoma (Surcula) rotundata, Wats. 

 Pleurotoma (Surcula) goniodes, Wats. 

 Pleurotoma (Surcula) plebeia, Wats. 

 Pleurotoma (Surcula) syngenes, Wats. 

 Pleurotoma (Surcida) liemimeres, Wats. 

 Pleurotoma (Surcula) anteridion, Wats. 

 Pleurotoma (Surcula) bolbodes, Wats. 

 Pleurotoma (Surcula) gypsata, Wats. 

 Pleurotoma (Surcula) dissimilis, n. sp. 

 Pleurotoma (Genota) didyma, Wats. 



1 As a name for the family Pleurotomaceag was published by Hinds (Voyage of the " Sulphur," p. 15, 

 1844), but entirely without definition. 



2 Turris of Humphrey, 1797, adopted by Adams '(Genera, vol. i. p. 87), is Turritella. Turns of Bolten, 

 1798, is Pleurotoma, but is only a catalogue name. 



8 I regret that the very valuable work of Bellardi on the tertiary molluscs of Piedmont, of which vol. iL, 

 1877, contains 674 species of Pleurotoma, did not come into my hands till so late a period as made any 

 thorough comparison of his Piedmontese fossils with any of the living species from the Atlantic basin impos- 

 sible, and yet it is obvious that such a comparison is absolutely needed. A freer interchange of the publications 

 of learned societies at home and abroad, of which the American Government gives so admirable an example, 

 would greatly facilitate such work. 



