FAMILY 3. MACROSTOMATA. 37 
branchie, have instituted a wide separation in the two genera just 
quoted. Deshayes distinguishes the first of these, together with La- 
marck’s Stomatia and Stomatella, as the Scutibranchiata; whilst the 
Sigareti are placed after the Neritacea in his order Asiphonobranchiata. 
De Blainville, on the other hand, for reasons of which we are not in- 
formed, assigns the Stomatie and Stomatelle to different parts of his class 
(Paracephalophora monoica), whilst we are unable at present to distinguish 
so much as a generic difference between them. ‘The Stomatie are united 
to the Haliotides in his order Scutibranchiata, and the Stomatelle follow 
the Sigareti in his order Chismobranchiata. 
The shell of the Macrostomata may be described as being a little con- 
voluted, and sometimes perforated with a regular series of holes; the 
spire is short and the aperture very large ; sometimes the shell is almost 
entirely enveloped by the mantle. 
We refer the four following genera to this family : 
VELUTINA. STOMATIA. 
SIGARETUS. Hatioris. 
VELUTINA, Gray. 
Testa subglobosa, hemispherica, epidermide tenui induta; spira parva, 
obtusa, submarginali ; apertura amplissima, rotundata, integra, 
margine acuto ; columella arcuata umbilicum minutum partim oc- 
cultante. 
The Bulla velutina of Miller, erroneously cited by Lamarck as a syno- 
nym of the Sigaretus haliotoideus, was selected by Gray for the formation 
of this genus; it was also proposed about the same time by De Blain- 
ville, upon examination of a specimen sent to him by Defrance. It is 
said to partake of the characters of Pileopsis and Sigaretus, and may be 
considered both interesting and important on account of the affinity 
