A STUDY OF CERTAIN CATERPILLARS. 



1239 



Characteristics. 



Tubercles hu;.'c ami l)ristly 



" iliiiiiiiisln(l, often without bristles 



" ohaiiireil to lenticles 



Lenticles ohaiisrod to spots 



No eonspieuoiis tubercles 



Filaments 



Body piettv uniformly cylindrical .... 



" sliirhtlv tumid in" front 



" distinctly " " •' 



" tJiperin^ in front 



Color almost entirely brown 



" dark, saddled with Iii;lit 



" transversely striped with black and bright 



" almost entirely fireen 



Curvinj; lateral stripe in front 



UriiTbt >pots in rows on abdominal scirments 



A tllt)l-;ici<' (iffllus 



Special markings on lirst ainlomlinil segment 



Papilio. 



1-3 



4 

 4 

 6 

 5 

 



1-3 



4-5 



1-3 

 4-6 







2-5 











From this it would appear to be tolerably clear that the primaeval cater- 

 pillar of the Papilioninae was covered with rows of fleshy, mammiform 

 tubercles beset with bristles, and that these were retained through life ; but 

 that in the gradual development of the group these were lost, first at the 

 final stage as we now find it in Papilio, after^vards at successively earlier 

 and earlier stages ; the loss consisting, first, in the removal of the bristles, 

 afterwards in the lowering of the tubercles until only smooth and shining 

 lenticles remained, as now in the full grown caterpillar of Heraclides ; 

 these again, as in several genera, were replaced by colored spots, some of 

 which, in caterpillars so far developed as Euphoeades and Jasoniades, 

 assumed special forms. 



So when we come to the general color, it may be fairly presumed that 

 the early caterpillar was of a dark color — in no way green as Weismann, 

 from liis study of the Sphingidae, seems to think all young caterpillars were ; 

 probably of a uniform dark color with a tendency toward a deepening of 

 the tint of the region about the third thoracic segment (which early assumes 

 a special importance in these caterpillars), and also about the seventh 

 abdominal segment, by the tendency of both markings and dermal appen- 

 dages to assume a polar arrangement in elongated forms. By this means 

 and through the intensification of these contrasts arose the lightening of the 

 middle parts of the body to form a saddle-shaped, whitish patch — a mark- 

 in"' surely of great antiquity in ' swallow-tail caterpillars, since it is now 

 found at birth in four of our six genera, and a fifth shows a tendency 

 toward it. This style of marking has been retained throughout life in 

 Heraclides only of all the members of our fauna ; and as it is in just this 

 genus alone that the lenticle-traces of the tubercles persist to maturity, we 

 have certainly in Heraclides the perpetuation of a very antiquated type. 



That in Papilio we have also a very persistent type may be judged from 

 the great stability of the upper tubercles, wliich are even not lost until 

 after the assumption of the changed livery of maturity, — a livery which 



