108 MURICID&. 
The typical Trophon has a fusiform shell, thin and white, the 
whorls with numerous, sharp, laminated varices, the interstices 
smooth, or spirally ribbed; canal open, usually turned to the 
left ; no umbilicus; lip thin, smooth within. This group is essen- 
tially boreal in distribution. There is, however, another group 
of species inhabiting the southern temperate and Antarctic zones, 
which, whilst possessing the main features of the type, the laminz 
and the white color, present peculiar characters. These shells 
are usually broadly ovate, shouldered, umbilicate, the aperture 
dark-colored within. They form a transition to Siphonalia, and 
might with almost equal propriety be included in that genus. 
Montfort’s definition of the genus Trophon, indeed, does not 
correspond so well with the typical group as now recognized, as 
it does with these Siphonalia-like shells. 
SuBFAMILY PURPURIN. 
The Muricide naturally subdivide into two groups, one of 
them : Murices) distinguished by varices on the shell, operculum 
with terminal initial point, whilst the other (Purpurie) has nodules 
but no varices, patulous columella, short canal or mere basal 
notch, operculum with lateral nucleus; yet on the confines of 
these two groups occur forms which partake of the characters 
of either, and the classification of which is entirely arbitrary. 
Ocinebra, species of Trophon, Urosalpinx and Hupleura have 
undoubted relationships with Purpura, yet are classed with 
Murex—partly because the species have usually been considered 
or were described as Murices ; on the other hand, Purpura cris- 
pata and its allies possess the variceal features of Murex. 
Kobelt has, on this account, included them in his catalogue of 
the genus Murex; but on account of the extreme variability of 
the species (some specimens being without varices) and the 
number of connecting forms between the smoother varieties and 
typical Purpure, I prefer to retain them in the group to which 
they have usually been referred. 
If the difficulty of defining these two subfamilies is great, 
still greater does it become when we descend to the genera and 
subgenera of either of them. Various authors have attempted 
it, from the “ groups” of Kiener’s monograph to the genera and 
subgenera of H. and A. Adams. I adopt the latter as a mere 
convenience, premising that nature presents her specitic forms 
here (as frequently elsewhere) in such continuous series, that no 
real line of demarcation can be traced; the characters selected 
represent simply the high tide of an osculation, which at its ebb 
merges into the next incoming wave. 

Purrura, Bruguiere. 
Syn.—Mancinella, Link. Microstoma,Swn. Thais, Link. 
