PIIYLOGENY OF FUSUS AND ITS ALTJES. 35 



series. (The author uses the terms variety and subvaricty here out 

 of consideration for those who constantly declaim against the sub- 

 division of species, on the ground that the subject is made too difficult 

 for "beginners." The author, however, maintains that these "varieties" 

 and "subvarieties" are entitled to specific rank, even though the inter- 

 mediate forms are all present.) 



The first distinct mutation is that corresponding to F. loni^icaudiis 

 var. torcumoidcs of the coins series. This, judging from the descrip- 

 tion, appears to be the mutation selected by Adams as the type of his 

 species. It is the mutation illustrated by Lischke on plate 11, fig. 3, 

 of part I of his work on Japanische Meeres-conchilien. In this speci- 

 men the round whorls are succeeded by subangular ones, which in 

 turn give way to nearly round whorls again. The ribs are absent on 

 the last part of the last whorl. In a young specimen (M. C. Z. 920) the 

 subdued angulation with its obsolescent nodules is continued to the 

 eighth or ninth whorl, where it is succeeded by a smooth keel, which 

 fades toward the aperture where the whorl is uniformly convex. This 

 specimen is very like the young of F. closter (pi. Ill, fig. i), dif- 

 fering from it chiefly in having its early whorls much less crowded than 

 is characteristic of that species. The young of these two species are 

 closely related. 



Figures 4 and 5 of Lischke's plate II represent a variety in which 

 the round-whorled, round-ribbed character continues to the end. This 

 may possibly represent a form which has never passed beyond the 

 primitive round-whorled tnrricnlus stage, but it is more probable that 

 it represents a highly accelerated individual in which the angular stage 

 is entirely suppressed. 



A specimen of this variety in the collection of the National Museum 

 (40650) is more slender than the majority of these shells. The early 

 whorls are well rounded, with round ribs, and strong sharp spirals, 

 which continue to the end. Intercalated spirals appear in the fourth 

 or fifth whorl, or even later (the apex of the shell being broken away), 

 and they are first seen between the two central ones of the primary 

 spirals. There is scarcely any angulation, a slight flattening of the 

 shoulder, and accompanying obsolescence of the ribs being the only 

 approach to it. The ribs occur at intervals, but they are very faint. 

 A long slender anterior canal occurs. 



This shell has a distinctly different aspect from the others of this 

 series. In outline, character of spirals, apical angle and character of 

 the anterior canal, it agrees closely with F. nova-hoUandicc from Aus- 

 tralia, but the young is rounded, instead of bicarinate. The specimen 

 is labeled from the Japan Sea. 



Two specimens in the collection of the Museum of Comparative 

 Zoology (920, 896) belong to this variety. In the first one the early 



