27 
only. Whenever they are also present on the abdomen, this will 
be mentioned in the description. But where type / is given for a 
certain family, this has no relation to the * setae. The type therefore 
consists of: 
Seta (ete.) dorsalis, oral and at the same time dorsal. 
S. subdorsalis superior, more caudal and in some cases also some- 
what ventral to the foregoing. 
*S. subdorsalis inferior, ventral to the preceding. 
—*S. dorsolateralis, on the oral border of the segment between s. 
dorsalis and s. suprastigmalis. 
S. suprastigmalis, above the stigma in a vertical line with s. dor- 
salis and s. dorsolateralis. 
*S. prostigmalis, anterior to the stigma. 
S. poststigmalis, caudal and usually a little ventral to the stigma. 
S. infrastigmalis, beneath the stigma. 
S. basalis anterior, and 
S. basalis posterior, between s. infrastigmalis and the insertion of 
the leg, or where this is absent, between s. infrastigmalis and s. pedalis. 
S. pedalis, on the base of the leg, or when the leg is obsolete, 
on the corresponding spot. I consider this seta as a proof of the 
secondary reduction of prolegs on the abdominal segments 1,2,7,8,9. 
The legs of the thorax and sometimes those of the abdomen are 
generally well provided with hairs. To these I did not give names, 
as they nearly always differ in shape and size from the above 
named primary ones, and so may be fairly considered of secondary 
nature. 
*S. propedalis, on the ventral side, before the anterior margin of 
the leg. 
S. ventralis, between the inner side of the leg and the ventral, 
median-line. 
The reductions, occurring within the limits of this type, generally 
are traceable in the ontogeny of one and the same species, or by 
comparison between the different species of one and the same family. 
The hinder abdominal segments usually differ a little frou. the type. 
The simplifications, corresponding with this deviation may be con- 
sidered as secondary modifications, though they often lead to pseudo- 
primitive arrangements. 
Type Ia. A simplification of very frequent occurrence is caused 
by the vanishing of the setae dorsales, the seta poststigmalis at the 
same time coalescing with the seta infrastigmalis. The result is a 
single series, in which the stigma also takes its place. This pattern, 
which at first sight seems to possess a primitive character, occurs 
