130 THE NAUTILUS. 
average of these three, given by such an authority, should satisfy the 
most exacting. 
The average of the examples given by Simpson, gives a per- 
centage of .556. The percentage which Rafinesque gives for 
viridis (5 to 9) is .555., 
A closer agreement is not to be found in the history of the Nairades ! 
Note—The translation of Poulson contains many errors. 
1. The dimensions, one and a half inch is that of the altitude, 
not as in Poulson. 
2. The lateral tooth is thin, not slender. 
3. The cardinal tooth is not divergent, but is decurrent—quite 
a different thing ! 
TURRITIDAE VS. TURRIDAE. 
BY S. STILLMAN BERRY. 
The unfortunate rehabilitation of the nondescript names of 
the Museum Boltenianum has brought about as one direct con- 
sequence the overturning of the time-honored generic name 
Plewrotoma Lamarck in favor of Bolten’s Turris. Accepting the 
change as most seem to have been impelled to do, it thereupon 
follows that since Plewrotoma was the typical genus of its family, 
a change in the generic name necessitates a similar alteration in 
the family name to conform. The reigning regulation in 
Article 4 of the International Code of Zoological Nomenclature 
is ostensibly so explicit regarding such matters as the formation 
of family names that at first thought one would not anticipate 
much disagreement among students in its specific application. 
In the instance under consideration, however, two opposing 
views have found t=eir way into print.’ Both cannot be equally 
correct, and since the family is an abundant one and frequently 
referred to, while a general principle of orthography is likewise 
involved, it becomes a matter of some importance to determine 
which of the two, as we may adopt the spelling Turritidae or 
Turridae, is strictly the proper form to use. Curiously enough 
1 NavTiLus, v, 23, pp. 131, 144. 
