68 PHYLOGENY OF FUSUS AND ITS ALLIES. 



the last whorls, and the spirals become sharp. This variety seems to 

 form a connecting link between this species and F. marmoratus. 



Localities: Brazil (M. C. Z. 945 type; 945a, 947, 948, Thayer and 

 Hassler expeditions) ; Florida? (M. C. Z. 946 Wurdemann shells) ; off 

 Cape Frio, Brazil (M. C. Z. 961, dredged in 35 fathoms, Hassler Ex.) ; 

 no loc. (M. C. Z. 949, 950, 950a) ; Suez? (B. S. 2506, Chickering coll.). 



FUSUS MARMORATUS Philippi. 



1847. Fiisus marmoratus Philippi, Abbildungen, Bd. 2, p. 120, pi. 24, fig. 7. 

 1847. Fusus marmoratus Reeve, Iconica, pi. i, fig. i, ib. 



The protoconch of this species has not been seen, but it is probably 

 of the nature of that of F. hrasiliensis. 



The conch begins with round whorls which are separated by 

 moderately deep sutures. They are shorter than wide. The ribs are 

 round, close set and reach from suture to suture. The interspaces 

 are concave and narrower than the ribs. In the next stage an angula- 

 tion appears, and with it intercalated spirals. The primary spirals are 

 narrow, sharp and distinctly subspinose on the ribs. With the ap- 

 pearance of the angulation the ribs become obsolete below the angle as 

 well as gradually above it. Sometimes, however, they persist to near 

 the end. 



In a specimen from the Gulf of Suez (M. C. Z. 942) the ribs are 

 strongly developed on the penultimate whorl, but become obsolete on 

 the body and shoulder of the last whorl. They remain strong, how- 

 ever, on the periphery, where they include from one to three spirals, 

 which are thicker and stronger than the others, and which produce 

 the noded projections on the keel. The coloration is mainly on the 

 ribs. 



This specimen represents the toreumus type of this species (series) 

 never passing beyond the primitive angular stage. It is the most 

 primitive variety of the species. 



In another specimen (M. C. Z. 943) the peripheral angulation is 

 formed by two strong spirals, of which the upper one is the stronger. 

 The anterior canal of this specimen is rather shorter than that of most 

 specimens. 



In the Red Sea occurs a variety (described below) which shows 

 some marked differences. It has been identified with F. midticarinatus 

 Lam. as figured by Kiener, but with this identification I q^n not agree. 

 It may be wise to separate this as a distinct species from F. marmoratus, 

 although it is difficult to state just wherein lies the difference. The 

 variation is not one due to acceleration in the development of a distinct 

 series, but is rather a variation in those characters which will produce 

 a new genetic series. In a refined classification the variation is to be 

 considered as generic rather than specific. Nevertheless, although this 



