318 TROCHID. 
. 
regarded as isolated, and if it is to be described at all, it ought 
to be done minutely in order to be correct. 
I prefer the finished painting to the crude outline, and so 
with an animal or shell. I repudiate the meagre lists of 
family, generic and specific names, devoid of description of the 
object ; yet we find such dishonest stuff sufficient to qualify its 
authors to head with their names a family, genus, or species, 
or at least to figure as the “ fortemque Gyan, fortemque 
Cloanthum,” in the serried ranks of worthless synonyms. 
Generalization of masses of objects of natural history is 
always a failure; the result is confusion and loss of identity ; 
and though now and then an epithet too many may occur 
in specific description, in such case a fastidious criticism may 
perhaps be dispensed with. 
I have reserved until the termmation of the descriptive 
notes, my remarks on the branchial apparatus and reproduc- 
tive organs of the 7rochi, as I hoped, in a very few words, 
contrary to my own doctrine, to generalize on these points. 
I am disappointed; some anomalies have presented them- 
selves which require further investigation. The branchial 
plume of the larger’ Trochi—I, cannot speak of the minuter, 
as they escape observation—are acutely pomted anteally, in- 
creasing in breadth posteally, to their arrival at the region of 
the pericardium. In most other Pectimibranchiata the reverse 
is the case; but perhaps this structure has a connection with 
the reproductive organs. The plume is usually long, tapering 
like a leaf to a fine pomt, and composed of one or more rows 
of short, drab-coloured, close-set strands, accompanied, we 
think, in some species by the rudiments of mucous fillets. 
As regards the reproduction, I believe that the sexes of the 
Trochi have always been considered distinct in each indivi- 
dual ; M. Cuvier states so; but I have failed to discover in 
the usual position, except in the very minute species, an ex- 
serted male organ, or a retractile one in the branchial vault, 
or stomachal cavity: the only organ that I can find, that has 
the least similitude to a male appendage, is a narrow, white, 
tough, gently arcuated, pointed filament, lining or attached to 
one of the sides of the branchial leaf, from base to point. 
