8i 
maxillae lie on their outer edge and somewhat dorsally. 
At their tip they have spines and a membranous 
lamella. The palps serve to close in the mouth cavity. 
(/) Labial Plate.— Or under lip of Meinert, is a 
conical toothed piece in the middle inferior line. 
This latter (and probably also the mandibular 
teeth and maxillary hairs and palps) differs much in 
different species (Fig. 28). It is generally of specific 
but sometimes may be of generic importance. 
The Anal Papillae. —Note the tracheae ramifying 
in these, the papillae being possibly gill-like in function. 
In Megarhinus , Toxorhynchites ,. Mucidus , Psorofhora , 
Lutzia , C. concolor , and C. tigrifes they are quite 
rudimentary. 
Culex. —(1) Examine in a glass dish and observe 
the hanging attitude of the larva and how the angle 
varies in different species, e.g., in C. concolor it is nearly 
horizontal. 
(2) Note with the microscope the absence of 
palmate hairs. 
(3) Note the position and extent of the antennal 
tuft, and shape of the antenna. The differences are 
not so striking as in the case of the syphon. 
(4) By the great differences in c syphonic index ? 
it is often possible to distinguish the different species. 
Important differences occur also in the scales of 
the pecten and comb. It is possible to subdivide the 
genus into groups in which these characters are more 
or less alike. 
Stegomyia. —The larva of Stegomyia is rather longer 
than that of Culex. When disturbed it exhibits a 
rather lashing movement like that of certain small 
aquatic worms. When at rest at the surface, the 
attitude of the body is almost vertical. The larva, 
however, spends a good deal of its time browsing at the 
G 
