24 ILLINOIS BIOLOGICAL MONOGRAPHS [256 



wall which bear setae. They are known as scoli, senti, parascoli, strumae, 

 verrucae, chalazae, or setae and vary greatly in form in the different 

 tribes and genera of the family. After a study of the larvae of the Chry- 

 somelidae, the probable progenitors of the Coccinellidae, one becomes 

 convinced that Chelymorpha shows perhaps the greatest resemblance to 

 the generalized coccinellids. In Chelymorpha each lateral margin of the 

 body is provided with a longitudinal row of long branched projections of 

 the body- wall. The distal end of each of these branches bears a stout seta. 

 Fracker in his work on lepidopterous larvae called structures similar to 

 these scoli. It was unfortunate, however, when he applied the same term 

 to a non-branched projection of the body-wall which bears setae upon its 

 trunk. These two structures are so widely different that they cannot be 

 considered as one and the same thing and for the latter the name sentus is 

 proposed. Fracker has also shown that the arrangement and number of 

 setae on the prothorax represents the generalized condition in lepidopterous 

 larvae. This may be true in coccinellid larvae, but there has been no 

 attempt made in this work to homologize the setae or the projections that 

 bear them. Since the arrangement of the setae in the various genera 

 differs, especially on the abdominal segments, this character has been 

 used to some extent in separating genera, and it is, therefore, necessary to 

 adapt a tentative nomenclature for these structures. This nomenclature 

 is based upon the conditions found in the third abdominal segment and 

 has been applied only to the segments of the abdomen. 



There is a seta or a projection bearing a seta or setae on each side of the 

 dorso-meson. These are designated as the dorsal group. The projection 

 on each lateral margin of the tergum is a dorso-lateral group, the one on 

 the dorsal portion of the lateral aspect is a lateral group, the one on the 

 ventral margin of the lateral aspect is the paralateral group, the small 

 group on each lateral margin of the sternum is a ventro-lateral group, and 

 the one on each side of the ventro-meson is the ventral group. 



The scolus is a branched projection of the body-wall, usually more than 

 five times as long as wide (Fig. 28). Each branch of the scolus bears at 

 its distal end a single stout seta. The dorsal and lateral surfaces of the 

 thorax and abdomen of Epilachna are provided with distinct scoli. 



The parascolus is a modification of the scolus in which the projection 

 is not more than three times as long as wide and usually not more than 

 twice (Fig. 30). This structure bears a few short branches which are about 

 as wide as long, each with a seta at its distal end. This modified scolus is 

 designated as a parascolus. It is found in Hippodamia, Coccinella, and 

 on the caudal segments of Anatis. 



A sentus is an elongated, cone-like projection of the body-wall which 

 is not branched like a scolus, but bears a few short stout setae upon its 

 trunk (Fig. 29). Fracker called this a scolus, but it differs decidedly in 



