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THE AMERICAN NATURALIST. [Vol. XXXV II. 



tal apparatus of Buccinum and Fulgur is very similar, and that 

 of Hemifusus and Melongena is nearly identical. In both groups, 

 the outer members or marginals of the adult odontophore bear 

 each one large and one or more small denticles, while the median 

 is supplied with small denticles only. In Fasciolaria and in 

 Fusus so far as known, the marginals are furnished with numer- 

 ous nearly equal denticles. If we assume that in the ancestral 

 type both marginals and median had one or at the most only a 

 few denticles, it is easy to see how the multidenticulate type 

 of modern Fasciolaria may be developed along one line, and the 

 similar type of modern Fusus along a parallel line. It is also 

 easy to see, that the heterodenticulate types of modern Buccinum 

 and Fulgur could branch off from the primitive fasciolarioid 

 ancestor, by the accentuation of the outer denticle of each mar- 

 ginal. Again the simple melongenoid type could branch off 

 from the primitive fusoid type, and develop by a similar accen- 

 tuation of the outer denticle. I see therefore no sufficient rea- 

 son in the similarity of odontophores for the present classifi- 

 cation of these genera, and instead of uniting Fulgur and 

 Hemifusus-Melongena in one familv. and Fusus and Fasciolaria 

 in another, I feel that the development of the shell characters 

 show very clearly the close relationship of Fusus and Hemifusus- 

 Melim-ena, and ot Faseiolaria and Fulgur, with Buccinum not 



