97] LEPIDOPTEROUS LARVAE — FRACKER 97 



members are particularly interesting as transition forms and their 

 structure is the clue to the peculiarities of the slug caterpillars. 



Head and cephalic part of prothorax retractile ; head very small, 

 slightly chitinized caudad of the fork of the epicranial suture; epicra- 

 nium marked by a transverse line between apical and occipital areas, 

 the former more heavily chitinized ; labrum with a small mesal emargin- 

 ation; fourth and fifth ocelli much larger than others, sixth ocellus at 

 a distance from first five; head setae sparse and slender. 



Body thickened in the middle, small at the ends, fusiform ; verrucae 

 large but flat. Prothorax with one large verruca dorsad of spiracle, one 

 small one (Kappa) in front of it, and two (Pi) at base of leg; mesothorax 

 with three verrucae. Beta group, rho, and epsilon, above that of the 

 Kappa group, Beta the largest; two verrucae forming Pi group at 

 base of leg ; metathorax with only two verrucae above that of the Kappa 

 group, epsilon and rho being fused; otherwise similar to mesothorax. 

 Abdomen with verrucae alpha and beta coalesced, kappa and eta 

 coalesced ; Pi group consisting of one verruca on segment 1 and of three 

 around the base of each of the six pairs of ventral prolegs. Spiracles 

 all circular, those of prothorax largest. Prolegs present on segments 

 2 to 7 and 10, those on 3, 4, 5, 6 bearing uniordinal crochets in two 

 groups, cephalic group the smaller; these two groups form an angulated 

 mesoseries in most cases but in one genus they are distinctly separated. 



Carama creiata. Fifth ocellus as far from fourth as from first; 

 two groups of crochets distinctly separated ; verrucae each consisting of 

 a thick group of short stiff setae and a few long slender ones. 



Lagoa crispata has the fifth ocellus dose to the fourth, the two 

 groups of crochets contiguous and the verrucae each consisting of a few 

 stiff setae and a great many slender ones. All the setae are subequal 

 in length. 



Megalopyge opercularis has the fifth ocellus rather distant from 

 the fourth and the crochets and verrucae as in Lagoa, The dorsal setae 

 of the ninth and tenth abdominal segments, however, are twice as long 

 as those of the first eight segments and form a conspicuous tail. 



Family CocHLionDAE. 



In tables it is rather difficult to separate the slug caterpillars from 

 the larvae of other Holometabola, but in nature the thick, short, fleshy 

 body and the minute thoracic legs will distinguish these forms from 

 all others. It should be remembered that there are no prolegs but that 

 the thoracic legs are always present. The different genera seem to have 

 little in common except the small retractile form of head. The arma- 

 ture has developed from verrucae, altho it often includes scolus-like 

 structures. Some of the genera are entirely smooth. 



