SPONGE. 279 
the parts of the mouth (trophi), which we have examined in Tipula, 
if we examine the corresponding parts in an insect in which they 
are more normal. Let us take the common cockroach. Here the 
mouth is bounded before by a median horny plate, the labrum or 
upper lip, and behind by another median plate, the labium, or 
lower lip, with soft foliaceous appendages, the labial palpi. At the 
sides of the mouth are two pairs of moveable jaws, an anterior pair 
of strong toothed cutting plates, without appendages—mandibles, 
and a posterior pair more foliaceous, the maxille, each provided 
with a large external palp. ‘The trophi, therefore, consist of a 
median labrum, a pair of mandibles, a pair of maxillee, and finally 
a labium, which really represents a second pair of maxillee, united 
by their basal parts. In Tipula the labrum and mandibles are 
represented by three minute pointed styles or setee contained in a 
' groove on the upper side of the proboscis, and invisible without 
dissection. The first pair of maxillze are represented by their 
palpi which have undergone no abortion, and the labium or 
confluent second pair of maxillee, forms the fleshy proboscis. 
SPONGE. 
JHE soft, tough, porous material which lends its name to this 
article is perfectly familiar to everyone, and most persons have 
a vague idea that it isa production of the animal or vegetable 
kingdom, the general impression being that it is due to an insect 
similar to the creature credited by popular fancy with the formation 
of coral. Indeed it is really wonderful how comprehensive the 
term “insect” is in the mind of the non-biological public. Just as 
any physical phenomenon which is not understood is unhesitatingly 
ascribed to electricity, so any animal smaller than a mouse, unless 
it be a fish, is an insect. But even this idea of the origin of 
sponges, vague and erroneous as it is, marks an advance on a pre- 
vious state, for it is not so very long since even naturalists of 
eminence, who had studied the sponge, were unable to agree as to 
its animal nature at all, many stoutly maintaining for it a vegetable 
origin. So for fifty years the sponge remained in purgatory unable 
to find a permanent place in either kingdom. Nor can the 
biologists of the present generation plume themselves very highly 
on their comprehension of the nature and affinities of this animal 
or colony of animals, which still remains in this year of grace 1884 
as great an “anomaly” as “the Conservative working man.” 
In taking up the study of this ‘‘form of life,” we must be prepared 
to descend very low indeed in the scale of life—almost to the very 
