28 PHYLOGENY OF FUSUS AND ITS ALLIES. 



FUSUS LONGICAUDUS Bory, var. TOREUMOIDES var. nov. 



(Plate II, figs. 2 and 3.) 

 Fusus coins and F. longicauda in part, of authors. 



This variety is intermediate between F. coins and F. longicandus. 

 It differs from the normal F. colus in having the toreumus stage weakly 

 developed or almost suppressed, while the longicandus stage is well 

 developed. It differs from F. longicandus in not having the toreumus 

 stage wholly suppressed. The toreumus stage is not so much con- 

 densed, as it is weakly developed over the extent of several whorls. 

 The coins stage is generally well developed, though often obscured by 

 the strengthening of other spirals. In a specimen from Ceylon ( M. C. 

 Z. 883) the tubercles are continuous nearly to the end, but throughout 

 they are faint, more as in the latter portion of F. coins. The last whorl 

 assumes the colus-longicandns characteristics. 



Sometimes the ribs reappear after they have disappeared, thus 

 showing reversion to an earlier characteristic. 



A specimen of unknown locality (M. C. Z. 908) belongs here. The 

 first whorl or two are broken away, and of the remaining, seven are 

 round with round ribs and uniform spirals. Intercalated spirals ap- 

 pear in the latter of these. On the succeeding whorls the ribs become 

 faint and practically disappear. A keel is gradually developed through 

 the strengthening of the lower of the two central spirals. The third 

 central spiral also becomes strong, giving the appearance of bicarina- 

 tion. From temporary reappearance of ribs the keel at times becomes 

 nodulose. 



Localities: Ceylon (M. C. Z. 883) ; no loc. (M. C. Z. 905, 908). 



FUSUS LONGICAUDUS Bory. 



(Plate II, figs. 4-6.) 



1816. Fusus longicauda Bory, Enc. Meth., pi. 423, fig. 2. 



1847. Fusus longicauda Reeve, Iconica, sp. 15. 



1881. Fusus longicauda Tryon, Man. Conch., vol. Ill, pi. 38, f. 157. 



This species forms the terminal member of the series. The first 

 nine or ten whorls of the conch are identical with F. tnrriculns in one 

 specimen (M. C. Z. 906, PI. II, fig. 6), while in others only seven or 

 eight whorls are in the turriculus stage. On the succeeding whorls 

 the striae or spirals become more prominent, the ribs becoming fainter. 

 This occurs generally first on the upper portion of the whorl, thus 

 giving a shouldered expression to the shell. After that the ribs dis- 

 appear entirely, and in the most typical specimen seen the last three 

 whorls are ribless and marked only by spirals of two series. Inter- 

 calated spirals appear on the seventh or eighth whorl, but do not 

 reach the strength of the primary ones. The central primary spiral 



