( Ixii ) 



iiioiitli-iiaits occur <;oiici'ally tojretlioi-, iiiul are acconipauieil liy the a])j)eai'aiice 

 of niii(i;liiu'ss in tlie scaling of the liead and often by the ai)i)earance of scales 

 on the pilifer and tongue in place of bristles and hairs. The roughness of the 

 scaling is here a sign of weakness of the s[)ecies, suggesting an analogy with 

 the shaggincss of weakly iiidiriduaU of mammals. 



Little lias liccn published bearing on the comjiarative morjiliology of the 

 tnnik of the tliorax of Le])i(loi)tcra, authors having confined themselves generally 

 to a comparison of the thorax of the Lephhptera Jiiynta with that of the 

 Frenata One of ns has given an account of the mesosternite of the Rliopa- 

 Incera* and tried to tinravel the homology of the various plates composing 

 the sternal i)art of tlie mesothorax. Our researches on tlie thorax of the 

 Jleterorera are not yet rijie for publication. The sterna of the various 

 Heterocevons families are more ('(pially developed than in tlie families of 

 Butterflies ; such sj)ecialisations as we have found there do not occur here. 

 But there are also in the J]eteroc<'ra thoracic characters distinctive of genera, 

 tribes, and families. The most variable part of the thorax within a Heterocerous 

 family is generally the metanotnm. We shall restrict our description to the 

 thorax of the Spkingidac. 



The denuded protliorax does not apparently offer characters of taxonomic 

 value in tiiis family. The mesonotum (PI. LXII. f. (i, dorsal view ; PI. LXIII. 

 f. ], lateral view), composed of the praescutum, scutum, and' postscutura 

 (= scutellum), is very large, as in most Frenata, occupying by far the larger 

 j)art of the notal region, the pro- and metauotum I eing quite small as compared 

 with the mesonotum. Tlie praescutum [psc) is distinctly triangular in dorsal 

 view, penetrating between the halves of the scutum, or it is transverse. It is 

 vertical iu lateral aspect. The scutum (;«.sr) is widest behind and little longer 

 than broad ; the mesial suture vanishes in front or is here vestigial. The 

 ])Ostscatnm {mscl) varies obviously in size and shajie (Pi. LXII. f. 0. 8), the 

 anterior and posterior angles being more acute in MacroglossKni, Sesia, and some 

 allies tiian in most other SphiiujUhtr. 



The praescutum of the metanotnm is not visible in the figures. The scutum 

 (mtsc) is divided like that of the mesonotum, but the two halves are widely 

 separate, the postscutnm of the mesonotum projecting between them. The 

 postscutum {mtscl) is always narrow. In Sesia and allies (PI. LXII. f. 6) it is 

 overlapped by the mesothoracical postscutum, which reaches to the first abdominal 

 tcrgite, while it is free in the otlier Spkingulae (PI. LXII. I 8 ; PI. LXIII. f. 1). 



The ventral jiarts of the meso- and metathorax are never so different in 

 size in any Frenata as are the nota, though also here the mesothorax is the 

 larger of the two. PI. LXII. f. 7 represents the mesosternite in a frontal 

 aspect, the dorsal and ventral mesothoracical endoskeleton (endosc) being visible 

 in the cavity of the thorax. The mesial j)lates of the sternite, the sternum (st), 

 and peristernum {pest) arc not completely separated from one another ; the 

 sternum is elongate-triangular ; thei-e is generally a small membranaceous area 

 * Vcrh. V. Intern. Zooh Congreu p. 81G. t. 1. 2. 3 (1902). 



