PHYLOGENV OF FUSUS AND ITS ALLIES. 147 



From the data at present available it seems most probable that 

 Fusiis mi^^rated westward across the Atlantic in early Tertiary times, 

 and that it crossed the isthmus of Panama, during Miocene or 

 Pliocene times, when that land body was submerged, and then, crossing 

 the Pacific, established itself in the Indo-Pacific province, where it 

 flourishes to-day. Thus the most typical Fusi, i. e., the species of 

 the colus series, appear to have migrated nearly around the world. 

 It might of course be argued that the species of this series might 

 have migrated eastward as far as the Indo-Pacific province, and that 

 the Miocene and Pliocene members of the series are still awaiting 

 discovery in Europe and Asia. This would leave the American species 

 unaccounted for, since the hypothesis of a migration across the Pacific, 

 in opposition to the prevailing currents, is hardly tenable. If it is 

 assumed that migration occurred both eastward and westward, the 

 very close similarity between the American F. eucosmius and the 

 Chinese F. torcnmns, which amounts almost to identity, is to be ac- 

 counted for on a hypothesis other than immediate genetic relation. 

 To sum up then, it seems most likely that the species of the Fusiis 

 colus series originated in the Eocene of Western Europe, and migrated 

 westward during Tertiary times, until they have all but belted the 

 globe, though their resting places were only at widely separated stages, 

 where favorable conditions allowed development. 



Turning now to the other series of Fusiis, we find even more diffi- 

 cult problems indicated in their distribution. The F. tuberciilatus 

 series belongs wholly to the modern fauna, and is clearly derived from 

 the F. coins series, probably through F. torcnmns. F. tuberciilatus is 

 at home in the Indo-Pacific province, occurring on the east African 

 coast and islands in the Red Sea, and on the Australian coast (Queens- 

 land). The northernmost branch of this series is at home in the 

 Japan seas, this branch comprising F. nodosoplicatus and variety, 

 and F. pcrplcxns and varieties. From this latter series seems to have 

 developed the Philippine Island representative of this group. F. 

 distans. The occurrence of this latter species together with its de- 

 scendant, F. clostcr, in the West Indian waters (Isle of Margarita) 

 is a most perplexing circumstance. Is it possible that this species 

 migrated around the Cape of Good Hope, up the west coast of Africa, 

 and thence across the Atlantic to the West Indies? Or can we accept 

 the much more improbable idea that the species migrated eastward, 

 across the Pacific, and the submerged isthmus to its present location? 

 The very slight differences between the West Indian and Philippine 

 representatives of the species (F. distans) suggests that migration 

 took place in the modern period, and one or the other of these paths 

 must have been chosen unless we can accept the very improbable 

 hypothesis of an independent origin of the species in the two waters. 



