PHYLOGENY OF FUSUS AND ITS ALLIES. 3I 



and it is continued for two and a half volutions. Then the tuhercles 

 disappear, and for something over half a volution only a keel occurs, 

 with the shoulder somewhat rounded again. The rounding of the 

 shoulder increases toward the aperture, at which the keel has prac- 

 tically disappeared (being indicated only by a strong spiral), and the 

 outline of the lip has become a uniform curve. Similar features are 

 shown by two specimens from Queensland (M. C. Z. 887). They are 

 of the broadly turreted type which characterizes this species. The 

 tubercles after continuing over two whorls become confluent into a 

 carina. These cases show that the same succession of stages occurs in 

 the series to which F. tubcrculatits belongs as in that to which F. 

 torcumus belongs. Both series undergo development in the same lines, 

 producing parallel species, which are identical in characters which 

 ought to be of specific value, but differ in characters of a higher 

 taxonomic degree. In an extremely refined classification the series 

 here designated would be considered as constituting distinct genera, the 

 recurrence, in each series, of forms with the same specific characters 

 being expected in conformity with the law of parallelism. The coins 

 species, exemplified by the individuals above described, is not perhaps 

 sufficiently established to become admitted to specific rank, according 

 to the prevailing opinions as to what constitutes a species ; neverthe- 

 less for convenience sake, in referring it to its proper place it will here 

 be designated as F. tuherculato-colus. 



In the Haines collection of the American Museum occurs a speci- 

 men even further advanced. In this the sharp nodes are entirely sup- 

 pressed, there being but a moderate angulation over which the ribs 

 continue to the ante-penultimate whorl. Altogether there must have 

 been seven or eight round whorls, followed by two angular whorls, 

 in which the ribs and nodes progressively disappear. The keeled 

 character is continued for about a whorl — though faint and with faint 

 nodulations — and is succeeded by nearly a whorl with round contour. 

 The aperture is gerontic. This approaches very close to the longicaudus 

 stage and might be called F. tnbcrculato-longicaudns for the sake of 

 distinction. The form shows that it belongs to the present and not to 

 the coins series. 



The coloration of F. tiiberculatus is a reddish-brown spotting be- 

 tween the tubercles. The shell is protected by a periostracum of a 

 light brown color, furnished with papillre at the points of intersection 

 of the spirals and the lines of growth. 



These shells are readily distinguished from the members of the coins 

 series by the shorter and more l)roa(lly turreted spire, and by the shorter 

 anterior canal. 



Localities: Indian Ocean (M. C. Z. 30) ; Red Sea (M. C. Z. 885) ; 

 Zanzibar (M. C. Z. 88y) ; .Mauritius (M. C. Z. 884); Queensland 



