OF CONCHOLOQY. 191 



directing attention to the most obvious distinguishing pecu- 

 liarities of the species, with occasional criticisms on the views 

 of other writers. It is also noted, under each species, in what 

 cabinet, mostly that of Mr. Cuming, the type specimen selected 

 for illustration is preserved. 



"The author's method of proceeding is as follows: Having 

 determined upon a family to monograph, his first step is to 

 select from the Cumingian collection a characteristic series of 

 specimens of all the species of one or more genera, every spe- 

 cimen during the past twenty years having been taken from 

 the cabinet under the supervision of Mr. Cuming himself, who 

 furnishes whatever information he may be in possession of, 

 either from transmitted sources or from individual personal 

 research. This information, committed to paper, is subse- 

 quently sifted and collated with other information, and applied, 

 as the working out of a monograph proceeds, to the respective 

 species. On the completion of a monograph, the particulars 

 of information are generalized, and their bearings on the dif- 

 ferent branches of the study are exhibited in the preliminarv 

 observations to each genus. For an elaborate example of 

 what it is intended to convey, the reader is referred to the 

 preliminary observations to genus Terehratula. For this rea- 

 son the letter-press of Plate I. of each genus is not prepared 

 until the monograph is completed, when it is issued along 

 with the title-page and index. The Cumingian specimens 

 having been selected, a search is then made among the speci- 

 mens of the British Museum and other cabinets for further 

 material, and the views of different authors as to their charac- 

 ters and affinities are examined and compared. The specimens 

 determined upon for illustration are now grouped in plates 

 for the artist; and the stones, when drawn on and printed 

 from, are carefully put away in racks, arranged in alphabet- 

 ical order according to the name of the genus. Many and 

 curious are the details of etching, proving, printing, etc. ; and 

 the statistics of quantity acquire an interest as the work pro- 

 ceeds. The 1890 stones employed up to the present time 

 weigh little short of seventeen tons; placed side by side, they 

 would extend to a distance of more than half a mile ; and if 

 raised flat one upon another, they would reach to the height 

 of the dome of St. Paul's. The number of impressions printed 

 from these stones is approaching half a million ; and the color- 

 ing is done entirely by hand, forming the livelihood of a 

 family of colorists, who follow their occupation from year to 

 year with an assiduity and interest worthy of a higher branch 

 of art. 



" The mode of publication is to issue monthly a Part con- 

 taining eight plates, price 10s. (or bi-monthly a double Part 



