MELVILL: THE PRINCIPLES OF NOMENCLATURE. A77 
Students of Henry and Arthur Adams’ work on ‘ Recent Mollusca,’ 
1853-58, will notice their preference tor the use of Humphrey and Bolten’s 
generic names, as well as those of Klein and Adanson. We have already 
given an account of the two latter ; the particulars of the two former are as 
follows :— 
In 1797 was published the ‘Museum Calonnianum’ of GEORGE HuM- 
PHREY ; it specified the contents of the magnificent collection of natural 
history objects collected by M. de Calonne, consisting of specimens entomo- 
logical, conchological, ornithological, and minerological, etc. Many genera 
were propounded, but only insufficiently defined. 
In 1797 JOA. FRiED. BOLYTEN published at Hamburg his ‘ Museum 
Boltenianum sive Catalogus cimeliorum ex tribus regnis Nature que olim 
collegerat. Pars prima continens animalia in spiritu vini adservata classibus 
cunctis item siccata queedam integra et fragmenta zoologica.’ 
Both of these authors proposed many genera, both suffer in not being 
properly descriptive ; and the names of both, unless adopted by Lamarck or 
other subsequent authors, must fall into desuetude. 
EuLIMA Asso, 1826. 
Melanella Du/resze, mss., Bowdich (Elem. of Conch., p 27). 1822 (non 
Swn., 1840). : 
Eulima 2sso, 1826. 
Pasithea Lea, 1835. 
Balcis Leach, 1847. 
§ 1 Leiostraca H. & A. Adams, 1853. E. subulata Donovan. 
§ 2 Bacula 7. & A. Adams, 1863. FE. striolata H. & A. Adams. 
§ 3 Vitreolina Monterosato, 1884. E. incurva Kenzer. 
§ 4 Acicularia A/onterosato, 1884. E. intermedia Caztrazne. 
§ 5 Haliella A/onterosato, 1878. E. stenostoma /effreys. 
§ 6 Arcuella Vevzl/, 1874. A. mirifica Mevz7l. 
Melanella Dufr. has priority of four years, but, as Prof. Dall, remarks, 
its type A7. Dufresnzz is subgeneric, possessing a distorted spire. Accordingly 
£. polita L. is still retained as the type of Risso’s genus, and J/elanedla 
Dufr. can be relegated as sectional, unless we sever the genus into two. 
I can only hope this process will be possible. To apply the term A/e/anella 
to a genus of shells of a pure ivory whiteness would be typical of the ‘ lucus 
a non lucendo’ principle of derivations. We are indebted to Prof. Dall 
for calling attention to this. 
XIII.—THREE SUGGESTED RULES FOR 
SYSTEMATISTS. 
I have confined my remarks at present mainly to the 
genera of mollusca, as any questions touching the species are 
far more complicated and involved. But there are three 
