149 



species is 109, including one or two of doubtful existence, and of 

 fossil, 24 ; and of the former 8 are found both in a recent 

 and fossil state. 



The only sectional division of the genus that has been 

 attempted, is that of Mr. Gray in the above proceedings. 

 This division is three-fold ; the two first of these depend on 

 the presence of the peculiar girdling or division of the whorls, 

 and which is very conspicuous in many species, but practi- 

 cally I fail to carry it out in detail. Some species also are 

 so excessively variable in this character, that M. Kiener has 

 described Terebra castanea as having girdled whorls, but has 

 figured it without them. The latter writer has not attempted 

 any grouping of the species in his monograph, and as he has 

 done so in most cases, we may venture to infer that he did 

 not see room for it here. 



It cannot be denied that among the numerous species are 

 several shells, which, taken by themselves, would furnish good 

 grounds for sectional or even sub-generic divisions. And if we 

 take T. maculata as the proper generic type, then T. lanceata, 

 T. armillata, and T. commaculata, seem to offer strong points 

 of difference, and good grounds for sectional heads. But, 

 with every wish to establish some such divisions, I have found 

 it impracticable so to group the species that there shall be 

 little or no doubt which section they belong to ; and, unless 

 this object is attained, I do not see any use in a division ; 

 science would not be benefited merely by selecting the salient 

 points and strong grounds of the exceptions, and leaving the 

 crowd to follow as they may. 



In geographic distribution the group is essentially tropical. 

 Indeed the exceptions are very rare. One species occurs 

 in the Mediterranean Sea, but it is an aberrant form. Another 

 is met with on the shores of the United States, but I am not 

 in possession of its northern range ; perhaps a few species 

 occur as extra-tropical on the shores of New Holland. 

 It will thus be seen, that few genera of similar bulk are so 

 excessively tropical. The species abound more particularly 

 in the Asiatic and Pacific Seas, are usually found in situations 

 of sands, sandy mud, or fine coral, often under a few feet of 

 water, though sometimes at greater depths ; and seem also to 

 be most fruitful in individuals, since where they inhabit, they 

 may generally be procured in great numbers. In their distribu- 

 tion about fifty-three inhabit the Asiatic and Pacific Seas, seven- 

 teen the American, and fifteen the African ; of twenty-four the 

 locality is unknown, and our information of the West Indian 

 species is most barren. Our knowledge of the native country of 



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