MELVILL : THE PRINCIPLES OF NOMENCLATURE. 475 
In the foregoing list only those genera have been mentioned which have 
a varied synonymy, or about which there is the least doubt, but we have not 
included either the Cephalopoda, freshwater Gastropoda, or the Pztlmonzfera, 
but these last have been or-are being so skilfully handled by Mr. H. A. 
Pilsbry in his monumental work on the ‘Classification of the Aelicide,’ 
as to render it unnecessary to recapitulate them here. This is by far the 
most thorough and complete investigation into the alliances and physiology 
of this enormous assemblage of mollusks, which have their species in every 
land, and whose number is legion. Great and radical changes in nomen- 
clature, especially generic, have, naturally, been found necessary. The result 
is a masterpiece of lucidity, and the arrangement is one that should be 
adopted at once in collections, both public and private. A rigid adherence 
to the law of priority has been followed in almost every particular. 
This list has no pretensions to be considered infallible, and I shall at 
any time be pleased to receive criticisms upon it; needless to say, the ex- 
amination of the works of Hermannsen, Agassiz, Marschall, and Scudder, 
place any compiler of such catalogues as these under a deep sense of obliga- 
tion to those authors. 
XII.—OBSERVATIONS ON PARTICULAR GENERA. 
SCALARIA Lamk., 1801. 
Scala K7lezw, 1753; Humphrey, 1797. 
Epitonium So/ten, 1798. 
Cyclostoma Lamarck, 1799. 7 ype C. scalare Lamk.=Turbo scalaris Z. 
Scalaria Lamk., 1801. ype Scalaria pretiosa Lamk.=Turbo scalaris L. 
Scalaria Lz7k, 1807. 
Scalarus A/¢ft., 1810. 
Aciona Leach, 1815. 
Cyclostoma Schumacher, 1817. 
SuB-GENERA. 
1 Clathrus Ofen, 1815. 7}fe T. clathrus Z. 
2 Cirsostrema Morch, 1852. Type S. varicosa Lams. 
3 Opalia HY. & A. Adams, 1853. Type S. australis Lams. 
4 Amea H. & A. Adams, 1853. Type S. magnifica Sozd. 
5 Acirsa Morch, 1857. Type S. Eschrichtii Hold. 
6 Constantia 4. Adams, 1860. Type S. elegans Ad. 
7 Psychrosoma 7. Canefr7, 1876. Type S. Gouldi Canefri. 
8 Janthoscala Aforxch, 1876. Type S. modesta C. B. Adams. 
9 Turbona Browne, 1876. ZypeS. lamellosa Lamk. 
I had worked out the synonymy of the above so far, when, upon refer- 
ring to the ‘Report on the Mollusca dredged by the U.S. Coast Survey 
Steamer Blake,’ by W. H. Dall,* I accidentally came across his masterly 
summary of the nomenclature of this genus. 
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Throwing out as untenable the name proposed-by Bolten, and the 
authority of Humphrey, as both being ‘ nomina nuda,’ Prof. Dall gives his 
* Bull. Mus, Comp. Zool., vol. xviil., pp, 299-306, 1889, 
