This species is remarkable for its relatively very large nucleus, which at once distinguishes 

 it from the allied species; the small number of ribs, distinguishes it moreover from the preceding 

 species; in this latter respect it reminds JtV. lathraica Sturany, which is quite different by its 

 smaller nucleus and has consequently a larger number of ribbed whorls, which are considerably 

 more gradate, the general shape is more conic in lathraica, oval in macrocephala. 



19. Nassa (Alectryon, Acictilina) crebricostata n. sp. PI. XX, fig. 3. 



Stat. 139. 0°ii'S., I27°25'E. Molucca Passage. 397 M. Mud, stones and coral. 25 Spec. 



Shell small, oblong-ovate, with a rather short spire, transparent-whitish. Whorls 6, of 

 which 3 from a large nucleus, with smooth, shining, convex whorls, with a thin peripheral keel ; 

 subsequent whorls convex, separated by a deep suture. Sculpture consisting of numerous fine 

 ribs, 30 or more on last whorl ; these ribs are narrower than the interstices and are crossed 

 by a groove below the suture, making the ribs beaded, and 1 1 flat lirae, which on the median 

 part of last whorl are scarcely perceptible on the crest of the ribs, but make them granulose 

 towards the base, 4 of them being stronger. Aperture oval, with an obtuse angle above; 

 peristome rather thin, with a thick rib externally, and 8 denticles interiorly, of which the basal 

 one is slightly stronger; columellar side with a thin layer of enamel, scarcely folded above, 

 with a few pustules near the base of margin, ending in a thin fold; canal wide, not very deep. 



Alt. 7, lat. 4 a / s ; apert. alt. (with canal) 3, lat. i 3 ^ MiÜ. 



This species resembles in shape in some points N. ovoidea, but is readily distinguished 

 by the much larger number of finer ribs, by its larger nucleus, more convex whorls and armature 

 of aperture; in some respects it resembles N. sporadica Sturany, which has however the whorls 

 much more gradate and much less convex than my species, moreover sporadica is much larger, 

 which character however may be of less importance, as but one specimen has been dredged. 

 N. stiplira Sturany has also more convex whorls but less so than in crebricostata, is more 

 gradate, has a smaller number of stronger ribs and much smaller nuclear whorls; the spiral 

 sculpture is less conspicuous on median part of whorls. Though it is not a very agreable task, 

 to describe so many allied new species, I have endeavoured in vain to combine them with each 

 other or with N. munda ancl allies. I could make no description fit for them all, unless I would 

 make use of a few unsignificant words. I have, though not without doubt, located them in 

 Alectryon, following Melvill, who places his N. collaticia in that subgenus, but on account of 

 their affmity with N. babylonica Watson, I added the name Aciculina adopted by Watson for 

 the latter species, which group has been considered by Cossmann, to be a subgenus of what 

 he calls the genus Alectryon. 



20. Nassa (Acictilina) babylonica Watson. 



Watson. Rep. Challenger. Part 42, Scaph. and Gastrop. p. 185, PI. 11, fig. 8. 



Stat. 52. 9°3'.4S., 119 $6'.7 E. Savu Sea. 959 M. Globigerine ooze. 9 Spec 

 Stat. 137. Channel between Makjan and Halmaheira. 472 M. Fine, dark muddy sand. 3 Spec. 

 Stat. 178. 2°4oS., i28°37'.5E. Ceram Sea. 835 M. Blue mud. 2 Spec. 

 Stat. 300. io°48'.6S., I23°23'.iE. Timor Sea. 918 M. Fine grey mud. 3 Spec. 



72 



