DESCRIPTION OF PLATES xxi 
rm, muscle to the salivary receptacle ; mx.p', intercranial maxillary process ; zm, 
muscle attaching maxillary process to the occipital region of head ; lm', muscle to 
base of labium ; In, nerve to the proboscis; Itr, trachea to the proboscis ; nttn, muscle 
to the base of the mandible. 
Plate XVI 1 1 
Fig. i. Semi-diagramatic sagittal section through the head and proboscis of the female Anopheles 
cost a lis ( x 200). Ibr, labrum ; ep, epipharynx ; /?, hypopharynx ; /, labium ; />' as- 
cending portion to the pharynx ; />", horizontal portion ; «, nerve to the proboscis ; 
oe, oesophagus ; tr, trachea to the proboscis ; s.r, salivary receptacle ; s.d, common 
salivary duct ; f.m, muscle to the salivary receptacle ; .v, chitinous ridge or under sur- 
face of ventral wall of the first part of the pharynx, from which (f.m) the muscle to 
the salivary receptacle arises ; l\ clypeus ; p.m, pharyngeal muscle ; Ibr.m, labral 
muscle inserted into the prolongation of the labrum ; e.m, epipharyngeal muscle arising 
from the fulcrum ; a, commencement of the labrum : below this on the upper wall 
of the pharynx are the ' taste papillae ' ; /, fulcrum ; s.o.g, supra-oesophageal ganglion ; 
i.o.g, infra-oesophageal ganglion ; s.o, specialized hairs ; mx.p, intercranial maxillary 
process ; v.c, ventral commissure ; d.v, dorsal vessel ; d.t, main trachea to the head ; 
e, eye. 
Fig. 2. Transverse section at the level of the junction of the first and second part of the pharynx 
shewing the group of specialized hairs ( x 5 50). />, pharynx ; z, that part of the exo- 
skeleton which is folded in beneath the eyes. 
Plate XIX 
Fig. 1. Semi-diagramatic longitudinal horizontal section of the head and proboscis of the female 
Anopheles costalis ( x 180). Inn, muscle to the pumping organ, the middle membranous 
portion of the pharynx ; zm, muscle attaching the maxillary process to the occipital 
region of the skull ; Itr, trachea and nerve to the proboscis; lm', muscle to the base of 
the labium, arising from the under surface of the maxillary process ; rm, muscle to 
the salivary receptacle ; sr, salivary receptacle and duct ; .s, V-shaped opening of 
salivary receptacle; hypopharynx, the salivary gutter runs along its centre; mx.p, 
maxilliary palp ; lm, origin of labellar muscle ; mx.p', intercranial process of the 
maxilla ; e, eye, 
FlG. 2. Section of the distal end of the labium and labellae ( x 410). ////, labellar muscle; 
/;//', longitudinal tendon of labellar muscle ; r, lateral chitinous ridge of the labium, 
from which the labellar muscles arises; a, chitinous process at the base of the labella 
into which the long tendon of the labellar muscle is inserted; //;, labella; In, 
the termination of the labellar nerve; g, ganglionic structure in the interior of the 
labella, shewing the fibres of the labellar nerve ramifying over its surface ; ch, coarse 
hairs projecting downwards between the labellae and arising from their inner surface. 
Fig. 3. Drawing of a cleared specimen of the distal end of the labium and of the labellae of the 
female Anopheles costalis ( x 390). Ib, labella ; /, labium ; g y groove on the upper 
surface of the labium in which the stylets are enclosed ; <•/, the labellae articulation, 
observe the angle for the insertion of the long tendon of the labellar muscle ; r, lateral 
chitinous ridge of labium ; tl, tip of the labium. 
