MACDONALD 
73 
General Classification of the Gasteropoda. 
I am thus insensibly led into the subject of classification, which I must say I approach 
with considerable diffidence, being fully conscious of the danger of falling into a dictator ial 
style, where the results of my own researches are at variance with the views of man y 
worthy cultivators of the science of Malacology. It is quite foreign to my present pur- 
pose to enter upon the analysis of any single system. Well-informed zoologists naturally 
make what they believe to be truthful selections from all available systems, and thus, as it 
were, compound their own creed; hence I have to deal rather with such matters as are 
generally accepted than with the tenets of particular men. In justice to Mr. S. P. "Wood- 
ward, I do not hesitate to state that the soundest general work on the Mollusca that has 
hitherto appeared in England is his little Manual published by Weale. There is more 
nature, truth, and judicious conciseness in all the descriptive parts than one is accustomed 
to meet with in works of this kind ; and, although I am sometimes at issue with him, 1 
trust that my opposition is never factious or merely for victory's sake. 
Mr. Woodward has availed himself of the characters afforded by the lingual dentition 
more extensively, I believe, than any previous writer, if we except Professor Loven ; 
but much remains to be done before these can be successfully applied in the denning of 
the natural families, and still more before all the genera of Gasteropods can be referred to 
their proper places in the system. In the following Table, showing the general nature 
of the lingual dentition and of the auditory concretions in the principal families, I have 
merely endeavoured to make a step in the right direction ; though I have little doubt 
that when the numerous errors which are always incident to attempts embracing so wide 
a scope shall have been cleared away, and the right exposition given of the value and 
bearing of assumed points of affinity, a system will result inferior to none in the whole 
department of Zoology in the truthfulness of its natural arrangement. 
Prom more extended study of the subject, since my former paper on the materials of 
classification was written, I have arrived at the conclusion that the nature of the contents 
of the auditory sacs is of minor importance to the primary characters of the lingual den- 
tition, as to whether it is elongated and strap-like, or broad and pavimental. Two cir- 
cumstances in particular suggest this view, viz. :— 1st. The close anatomical relationship 
existing between Cerithium and Pkmaxis, and even the almost actual similarity of their 
lingual teeth, although the auditory sacs in the former contain otoconia and in the latter 
spherical otoliths. 2ndly. Several of the Eolidce (if I am not mistaken, I think I may 
venture to add the genus Flabellina) have otoconial particles, while the others in general 
have otoliths. It cannot be supposed, however, on this account that the few belong to a 
different family ; for their whole anatomy refutes such a supposition. 
I may remark that amongst the Doridce also I have observed the occasional occurrence 
of minute otoliths instead of otoconia. It is worthy of note that the otoliths, wherever 
they occur in such families as usually present otoconia, are exceedingly small, like the 
single primordial otoconial particle of the young Tteropod or Xiidibranch ; and in the 
converse examples, as in the Cerithiidce, where the presence of otoconia might a priori 
be quite unexpected, they are, as a rule, both few and large. 
vol. xxiii. L 
