CLASSIFICATION. 15 
it has always been found of a testaceous substance ; for these 
reasons, though we have doubted, we now think that the 
Bulla hyalina, the Amphisphyra of Loven, may be a true 
Bulla. 
Bullea, an wndoubted branch of this family, is copiously 
illustrated in our account of B. aperta, and by recent full de- 
scriptions of B. pruinosa, B. catena, and B. punctata, origin- 
ally published by us more than twenty years ago, in vol. iii. 
p- 339 of the Zoological Magazine. 
With respect to the Conovuli it has been said, that except 
Carychium, they are bisexual. We do not think so, as, be- 
sides their close connection with the Helices by the respiratory 
structure, we observed in more than twenty examples of the 
Pedipes bidentatus that all had well-filled ovaria. We believe 
they are congressional hermaphrodites ; at least for the present 
we consign them as members of that reproductive character. 
In consequence of the curious discovery, if it be substan- 
tiated, which is related in the chapter on the Trochide, that 
all the Pectinibranchiata, with circular multispiral opercula, 
hitherto considered bisexuals, are like the Helices hermaphro- 
dites with mutual congression, the Trochide, including the 
genus Valvata, and the new family of the Vermetide, con- 
taining the genera Cecum and Turritella, are admitted into this 
division. It seems, however, inexplicable why the strictly 
circularly operculated Pectinibranchiata should have the ge- 
nerative system of the Helices, and that all the others, of 
whatever shape the opercula may be, otherwise than circular, 
should be bisexuals. 
Though the other hermaphrodites, with mutual congression, 
as the Limneade, Limacide, and Helicide, are admitted into 
our main line, it is impossible to place them therein satis- 
factorily ; they are an aberrant group; nevertheless they form 
amongst themselves a closely connective line. The remaining 
hermaphrodites are the marine Pleurobranchus, Aplysia, Bulla, 
Bullea, and Otina? These are another aberrant tribe ad- 
mitted into line, but equally intractable as the last, yet they 
are pretty closely allied to each other. It appears then, that 
the general bond of consentaneity between all the families of 
