OF THE MOUTH PARTS OF CERTAIN INSECTS. 187 
head sclerites. Supported upon the cardo is the stipes or foot-stalk, deriving its mus- 
cular attachments largely from the cardo; but to some extent from the head itself, and 
this feature is a variable one. Surmounting the stipes is a palpifer or palpus-bearer, 
to which is attached a palpus, varying in the number of its joints. This derives all 
its muscles from the stipes in the typically developed maxilla. On the inner side of 
the stipes is attached the subgalea, deriving its muscles from the head in large part ; 
and this bears a two-jointed galea or hood. It is a matter of some importance to note 
that this galea is never more than two-jointed under any circumstances, and that the 
tendency is to maintain that number ; though in many instances it is reduced to one 
only. It is the most persistent as well as the most variable of the maxillary struc- 
tures, and is present when any of them exist at all. Inside of the subgalea, and 
attached to it as arule, is the lacinia or blade, which may or may not bear a digitus or 
finger. In the figures just cited we find what may be termed a normal or proportionate 
development of all the parts, in which no one sclerite is unduly developed or special- 
ized. Before attempting to study specializations it is important to note that, when 
carefully examined, the sclerites are seen to be arranged in three parallel series. That 
is to say three separable parts have grown together laterally, and this union bears with 
it the possibility of future disunion or separation for special purposes. We have as the 
inner series lacinia and digitus; as the middle, subgalea and galea; and as the outer 
the cardo, stipes and palpifer with the attached palpus. Now if we examine some of 
the Neuroptera, e. g., Stalis (Pl. II, Fig. 16), we find this lateral arrangement very 
strongly marked, and it is easily understood that each of these parallel sets may have 
their own peculiar limitations, and that each may be separately and independently 
modified. 
But lest this seem, after all, a far-fetched conclu<ion, let us examine the maxillee 
of Bittacus strigosus (P1. III, Fig. 4”), and we find almost exactly the hypothetical 
state of affairs actually existing! Lacinia, galea and palpifer all separated, of nearly 
equal length, but of quite different appearance. ‘The appearance of a transverse sec- 
tion made at about the middle is shown as Fig. 4”. Fora generalized type this form is 
especially valuable, and we may fairly use it as a guide in our discussion of maxillary 
possibilities. 
There is no absolute rule in the matter, but usually the galea tends to become the 
dominant maxillary organ. In many Neuroptera, and especially in their larval stages, 
the laciniate structure is best marked, as illustrated in Pl. III, Fig. 9, representing 
the maxilla of a Perlid larva Here the galea is reduced to a subordinate rank, and in 
many predaceous Coleoptera it is truly palpiform. 
In many Orthoptera the development of the galea justifies the name by forming 
