GASTROPOD PROTOCONCH. 185 
Veloconch.—tThe greater portion of this is formed during 
the veliger stage, though it may have been begun just before 
that stage ; it is, in fact, that portion of the protoconch which 
is formed subsequently to the flattening out of the primitive 
shell gland and before the velum commences to be aborted. 
It may be either corneous, as in Lotorium and Scaph- 
ella, and shed at an early stage; or calcareous, as in Tri- 
phora, and retained, or lost in the normal and almost 
universal decollation of apical whorls. 
Nepioconch.—This is formed during the nepionic stage. 
I have ia Number III of ‘Notes on Prosobranchiata’ 
given reasons for regarding the varix sometimes thrown up 
at the conclusion of the veloconch as the only example of a 
true nepioconch. 
Neanoconch.—'The neanoconch, or perhaps more pre- 
cisely the ananeanoconch, is formed during the ontogenetic 
stage from which it takes its name. 
In Lotorium it is moulded inside the horny veloconch. 
In Scaphella (fide Dall) the veloconch is a round corneous 
bulb; the neanoconch is not moulded in this, but consists 
of three or four caleareous whorls formed by the free edge of 
the mantle, and having a pointed nucleus, which is formed 
in the veloconch, but not moulded in it. In Megalatractus 
aruanus (Linn) there are somewhat the same conchogenetic 
stages; the neanoconch of five whorls is formed by the 
free edge of the mantle, whilst the corneous veloconch 1s cast 
in lime and generally shed before the creature leaves the egg 
- capsule. 
c. APPLICATION OF THE NOMENCLATURE. 
I now proceed to apply this nomenclature to a few proto- 
conchs of which descriptions and figures have been published. 
In Clausilia, according to Gegenbaur, on the authority 
of Lankester (7), the primitive shell is retained, so that 
here the protoconch consists of, at least, phyloconch and 
veloconch. Lankester, also, mentions other instances of the 
