
696 THE AMERICAN NATURALIST. | [Vor. XXXVI. 
It is obvious that these long slender imaginal mouth parts 
cannot be contained within the very much shorter and alto- 
gether smaller larval parts. As a matter of fact, the whole 
imaginal head is for simple mechanical reasons forced to lie 
during its development chiefly in the anterior larval thoracic 
segment, the anterior portions, including the antenna and 
mouth parts, projecting forward into the larval head capsule. 
But still there is indicated perfectly the correspondence 
between particular imaginal parts and particular larval parts 

Fic. 14. 
Fic. 15. 
Fic. 14. — Mouth parts of adult digger wasp, A mmophila sp. aan mer and labial palpus 
. left side, in figure, not drawn). szd., mandible; zx., m .p., maxillary palpus; 
sies maxillary lobe; 77. labium; /2.Z., labial ET. pe pvc pg, paraglossa ; 
= 
E 
Fie. 15. cam a old larva of digger wasp, Ammophila sp., cleared to show forming imaginal 
à within. /.c., larval head wall; Z4, forming imaginal head; z.e., imaginal eye; 
z.ant., imaginal antenna; Zmed., larval mandible; 7.»:d., imaginal mandible; Z.»x., larval 
maxilla ; erage 2 tmx. Ż., imaginal er palpus; ZJj., larval labium; 
i.li., imaginal labium; zJZ5., ginal labial palpus 
by the fact that the projecting tips of the elongate imaginal 
parts penetrate or lie within the short larval parts. This is 
shown clearly in the cleared and stained heads prepared by Mr. 
Spaulding, as well as in series of sections. Fig. 15 is drawn 
with camera lucida from one of the whole head preparations, 
and, as indicated by the lettering, those parts of the imago 
which we have, on the basis of comparative anatomy, assumed 
to compose the labium, do project into and correspond with 
the larval labium; the case is similar with maxilla and man- 
dibles. But, in origin, these imaginal mouth parts arise as 

