248 CRETACEOUS GASTROPODA 
The relations of the Sozarzzp# to other PROSOBRANCHIA are very differently 
interpreted. Many conchologists still adhere to the old opinion, that they must 
be classed only as a genus in the family Trocxzpm; others acknowledge them 
as an independent group, but still as close in the neighbourhood of the same 
family. 
The principal support for this was said to consist in the form of the shells, 
although the non-pearly structure of the same may be probably of greater import- 
ance, than the form itself. Since, however, the organisation of the animals in both 
these families has been made better known, this older classification must be 
abandoned. Gray has stated, that the proboscis of Solariwm is long and retractile, 
the tongue probably unarmed and the tentacles folded, in consideration of which 
characters he and H. and A. Adams consider the family as closely allied to the 
Pyraurpetiws and Crerrruropsip%. Although this classification cannot be seri- 
ously objected* to, specially when the non-existence of lingual teeth may be proved, 
still it is very difficult to bring the respective shells in close relative connection, 
without excluding forms which are evidently more correctly referred to the last 
mentioned two families. We have consequently thought it preferable to treat of the 
family after the Szzzqvarmp# and Owosrip“. The animals do not, of course, 
exhibit a very great resemblance, because the Sizzqgvarmp# have in consequence of 
their sessile life a rudimentary foot, but as regards the general form of the thickened 
tentacles, the eyes and the mantle, they do not essentially differ. The form of the 
foot could be better brought into comparison with that of the Cacza. The 
dentition has, I think, been examined only in one cr two species of the Vzruarrpz, 
but not in the Szzrevarizp; it cannot therefore be quoted as a point of comparison. 
Quoy and Gaimard (Zool. Astrol. Vol. III, p. 281) were the first who made 
known the animal of the Sozarmpm, and placed Solarium in the neighbour- 
hood of Vermetus, although they state that, from what they know of the animal, 
it does not change the generally accepted idea of the classification of the genus 
with Zrochus in the same family. There are, however, several points in organisa- 
tion, which support the classing of the Sozarmp in the place, assigned to them 
(perhaps accidentally) by the two authors of the Zoology of the Astrolabe. 
The operculum of Zorinia is in every way similarly formed to that of Siliquaria ; 
it could scarcely be compared with that of any other genus of the PROSOBRANCHIA. 
The operculum of Solariwm proper very much recalls, on the other hand, that of 
the ceriraun”. The usually crenulated edge round the umbilicus, terminating at 
the aperture with a slight insinuation, appears to indicate at least some kind of 
analogy with the slit of the Szzrqvaripx. A few fossil species of the genera Hecy- 
liomphalus, Bifrontia, and others, exhibit, in the total or partial dissolution of the 
whorls, a very close resemblance to the Szziquariupx, Veruetipz and Corba, 
which may also be brought in support of the classification of the Sozarmp# in 
this place. 
* Vide general notes on the Hotosromata, p. 208. 
