THE three extensive families of mollusks monographed in this 

 volume of the Manual of Conchology, include several of the 

 most beautiful of the marine genera. The material upon the 

 study of which I have based my text is unusually ample, enabling 

 me to make numerous satisfactory adjustments of the synonymy, 

 and to illustrate many variations in addition to the typical forms 

 of the species. It is hoped that the figures will enable naturalists 

 to identify their specimens with facility and certainty. Excep- 

 tion has been taken to some of the figures heretofore published 

 in this work, on the ground that they are uncharacteristic in 

 drawing and coloring : these illustrations are faithful copies of 

 the original (or typical) figures, such as I almost invariably give, 

 if published; and they are supplemented, whenever it is possible 

 to do so, by better illustrations of the same species. 



The next volume of the Manual will be devoted to the im- 

 portant group of the Toxifera including Cancellaria, Terebra, 

 Conus, Pleurotoma. Towards its completion 1 again ask the 

 kindly aid of authors and collectors, who may possess unfigured 

 or critical species. 



January, 1883. G. W. T., JR. 



