198 SOME SINGULAR THINGS 



rule the hairs, spines, filaments, or what not, are 

 highly developed upon the thoracic segments, some- 

 times increasingly so from the hindmost forward, the 

 series culminating in lofty bristles or long append- 

 ages upon the first thoracic segment. When this 

 occurs, it is an almost invariable rule that a simi- 

 lar but reversed arrangement and extension of the 

 same class of appendages is found upon the termi- 

 nal abdominal segments. Or if, as is frequently 

 the case, the second or third thoracic segment is 

 independently enlarged or its armature specially 

 magnified, a similar but generally lesser develop- 

 ment will be found to occur on one of the pre- 

 terminal, though not the terminal, abdominal 

 segments. A case in j)oint is easily seen in the 

 caterpillars of the genus Basilarchia, where the 

 second and third thoracic segments are mammilate, 

 and the second is crowned by a pair of stout, 

 thorny tubercles. So, too, in a less degree, the 

 seventh and eighth abdominal segments are slightl}^ 

 hunched and the corresponding tubercles at that 

 point are noticeably enlarged, esj)ecially on the 

 eighth segment. 



Many other similar features might be pointed 

 out even among the limited series of our own cat- 

 erpillars, as in all the young Pai^ilioninae, and this 



