THE LACINIA IN THE MAXILLA OF THE 
HYMENOPTERA.* 
By Avex. D. MAcGILLIvRAY, 
University of Illinois, Urbana, Illinois. 
The maxilla of biting insects consists of six pieces. There 
is at the proximal end a two segmented cardo (c), which articu- 
lates the maxilla to the head capsule (Figs. 1 and 27). Attached 
to the distal end of the cardo there is in the cockroach 
(Fig. 1) a rhomboidal-shaped piece, the stipes (s). The stipes 
in the locust (Fig. 2) is also rhomboidal in outline but is limited 
in its articulation to the mesal portion of the cardo. There is 
borne at the distal end of the stipes in the cockroach a two-seg- 
mented, somewhat bent tongue-shaped piece, the galea, (g). 
The galea of the locust is also two-segmented but borne at the 
distal and lateral margin of the stipes. At the proximal end 
of the galea against the lateral margin of the stipes, there is a 
small sclerite, the palpifer (p), which bears the five segmented 
‘maxillary palpus. The proximal segment of the galea and the 
palpifer in the locust constitute the lateral margin of the stipes. 
There is borne at the distal end of the stipes on the mesal side 
another appendage, which bears three prominent teeth at its 
distal end. This is the lacinia (la). The arrangement of the 
parts in the maxillz of biting insects is for all practical purposes 
identical with the above description and the figures of the 
maxilla of the cockroach and the locust, showing two distal 
pieces, a lacinia on the mesal side and a galea on the lateral 
side, with a segmented maxillary palpus attached on or near the 
lateral margin at the proximal end of the galea, and is character- 
istic. 
If the maxilla of Macroxyela infuscata (Fig. 3), one of the 
most generalized members of the order Hymenoptera, a ten- 
thredinid, known to me, is compared with that of the cockroach 
*Contribution from the Entomological Laboratories of the University of 
Illinois, No. 29. 
{The cardo of Melanoplus differentialis as here figured shows a narrow prox- 
imal piece with two projections at its proximal end; the shorter piece articulates 
against the ectal surface of the head capsule and the larger piece passes beneath 
the margin of the head capsule and serves for the attachment of muscles. These 
pieces are characteristic of this and some other species. It has been overlooked 
because it usually remains attached to the head capsule when the maxilla is 
removed. 
231 
