igo6] KNAB— NOTES ON DEINOCERITES CANCER THEOBALD 
97 
ps.ndages. It is this transverse ridge with its supporting chitin laterally ex- 
panded that forms the projecting angles so characteristic of Dcinoccrites. The 
same lateral expansion of this region occurs again in the larva of the Sabethid 
Lcsticocaiupa huuita Theobald. The modification of the ridge into rounded 
lobes, outward from the ma.xillae. as illustrated in the accom])anying figure of 
Janthinosoma jainaicciisis. occurs in most mos(|uito larvae but may be absent, 
as in Psoroplwra. The mandibles are truly most strikingly modified in 
Dci)iocerites but they are by no means unique, as Miss Mitchell asserts. 
There are no less than five species of Cnle.v known to the writer which 
present similar modifications in the form of the mandibles. A mandible of 
one of these species, Cnlcx vector Dyar Knab, drawn by Miss Mary Carmody, 
is here reproduced (fig. 3). It will be noted that the basal portion of the 
mandible, instead of being rounded off as is the case in most mosquito larvae, 
is drawn out into a slender straight projection which corresponds to the curved 
projection in Dcinoccrites. The toothing of the cutting surface of the mandibles 
shows various modifications, particularly in the tropical species examined by the 
writer, but it is doubtful that they will have any classificatory value. 
iMiss Mitchell has fallen into error in her description of the labial plate of 
Dcinoccrites. There are three of these structures, overlapping each other, 
present in Culicid larvae. Usually the outer one of these plates is the stoutest 
and heavily pigmented so that it obscures the other two which are more 
delicate and transparent. It is this outer heavily chitinized plate which has been 
made use of in descriptive work, while the other two have remained un- 
noticed or at least disregarded. It is one of these inner plates that iMiss 
Mitchell describes in her article. The outer plate is perhaps difficult to find in 
dissecting, but it is obvious enough when the entire head is examined ventrally. 
It is usually small, and pale like the head integument, but its general form 
corresponds with that of other mosquito larvae. It may be remarked in con- 
clusion that Raschke (Die Larve von Culex nemorosus 1887) does not consider 
this plate a labial structure but as belonging to the integument of the gular 
region. M. T. Thompson has recently expressed the same belief and terms 
the part “mental sclerite,” ( Proc. Boston Soc. Xat. Hist., v. 32, p. 170). 
