LEPIDOPTERA. 709 



closed in certain species and the stomach sometimes aborted, but 

 other species suck up the sap and juices of plants by means of a 

 pumping organ in the head. 



The three thoracic segments are firmly fused together. The 

 prothorax is reduced to a mere ring, but bears on its upper side 

 a pair of process termed patagia. The mesothorax is very 

 large and is bounded behind by a large scutellum. Just in front 

 of the insertion of the fore-wings the mesothorax bears on each 

 side a small flap, the tegula, which overhangs the articulation of 

 the wings. The metathorax is comparatively small. In the 

 female seven abdominal segments may be made out ; two more, 

 and possibly a trace of a tenth, are tucked into the seventh. In 

 the male eight segments are externally visible. The legs are 

 slender, covered with scales ; the tarsi have five segments. 



The fore-wings are larger than the hind- wings ; in some species 

 both pairs appear larger than they are owing to the scales over- 

 lapping the edge of the wings. The males are invariably winged, 

 but in rare cases, e.g. the Winter moth Cheimatobia bnunata, the 

 female is wingless. The fore- and hind-wings of each side are 

 either correlated by a bristle the frenulum projecting from 

 the latter and fitting into a flap or a bunch of stiff hairs the 

 retinaculum on the former ; or the hind-wing has a shoulder pro- 

 jecting forward under the base .of the front wing ; or thirdly, 

 in some moths without a frenulum, the fore- wing has a small 

 lobe at its base, called the jugum, which droops towards the 

 hind-wing, and which may slightly help the two to work 

 together. Each wing has almost always one cell, or area com- 

 pletely surrounded by nervures ; the latter are much more 

 numerous at the outer margins than at the bases of the wings. 



There is a pumping apparatus divaricated by muscles in the 

 head ; the oesophagus traverses the thorax and opens into a 

 tubular stomach, which is preceded by a crop. A diverticulum 

 erroneously called a sucking stomach opens into the oesophagus. 

 The intestine is slightly coiled and ends in a large rectum. Three 

 malpighian tubules open by a common duct into each side of the 

 alimentary canal. The heart is looped both at its point of entry, 

 and within the thorax. There are three thoracic ganglia close to 

 one another and four abdominal ganglia. As a rule there are four 

 egg-tubes in each of the two ovaries, and the two oviducts open 

 by a single orifice at the end of the body. In front of this on the 



