PIIYLOGENY OF FUSUS AND ITS ALLIES. 79 



APTYXIS PROVENCALIS (Risso). 



1824. Fusus provencalis Risso, Hist. Nat. L'Europe IMer., T. 4, p. 207, pi. 9, 



fig. 131- 



1825. Fusus provencialis de Blainville, Fauna Frangaise, Moll., p. 87, pi. 4D, 

 fig. I. 



No specimens of this species have been seen, but the illustrations 

 given by Risso and de Blainville show clearly the characteristics of 

 this species. It appears to be a primitive Fusoid with simple ribs and 

 spirals, the latter only in primary scries. No angulation or keel ap- 

 pears, and the ribs continue to the lip. The canal is short and slightly 

 flexed, corresponding to that of A. syracusanus, to which this species 

 probably has ancestral relations. This relation was pointed out by 

 de Blainville. 



Accepting this relationship, the suggestion presents itself that this 

 species is the connecting link between A. syracusanus and primitive 

 members of the F. rostratns series of the same fauna. This relation may 

 be tentatively maintained until more material can be studied. 



Locality: Provence, Mediterranean coast of France. 



. APTYXIS SYRACUSANUS (Linnaeus). 



1767. Murex syracusanus Linn.«us, Syst. Nat., ed. 12, t. i, pt. 2, p. 12. 



1847. Fusus syracusanus Reeve, Iconica, pi. 3, sp. 10. 



1868. Latyrus (Aptyxis) syracusanus Troschel, Gebiss der Schnecken, vol. 



2, p. 64. 

 1883. Fusus syracusanus Kobelt, Europiiische Meeresconchilien, 3, p. 50, pi. 9, 



figs- 3-5- 



The protoconch of this species is not preserved in sufficient per- 

 fection in the specimens examined to allow accurate determination. It 

 appears to be typically Fusoid. 



The conch begins with rounded whorls which suggest Fusus 

 provencalis. The ribs of the early stages are broad and relatively 

 close together, being less than their width apart. They are not very 

 strongly marked by the spirals which are best developed in the inter- 

 spaces. These interspaces are deeply colored. Intercalated spirals 

 usually appear with the angulation, which in the less accelerated indi- 

 viduals begins late. It is brought about by the increase in thickness 

 of the two central spirals which at first are similar. Later, however, 

 the upper one increases in strength, and the shoulder becomes slightly 

 flattened. The ribs at the same time become fainter except at the 

 center, where they form nodulations at the angle. 



The angulation increases through flattening of the shoulder, and 

 through a corresponding flattening of the sides of the whorl, thus 

 producing a rigid angulation. The ribs continue across shoulder and 

 body of the whorl. 



The most advanced specimens are characterized, in addition, by 



