CHILOPODA. 



595 



which is covered by a cephalic plate (cephalite), carries four 

 pairs of appendages, and the first segment of the body is in 

 relation with the head by its appendages, the poison claws, 

 which are called maxillipeds. The tergal plate of this segment 

 is either absent, or weak, or well developed, in which case it is 

 known as the basilar plate (lamina basalis). The segments 

 behind this, except the two last, are much alike (see below) and 

 each carries one pair of legs. The last two are apodal and bear, 

 the first of them the median generative opening, the last the 

 anus. In the Lithobiidae and 

 Scutigeridae some of the tergites are 

 smaller than the others, and in the 

 Craterostigmidae there are six ter- 

 gites intercalated between the ter- 

 gites of the pedigerous segments. 

 The number of pedigerous body- 

 segments varies considerably : the 

 smallest number is 15 segments 

 in Craterostigmidae, Lithobiidae, 

 and Scutigeridae, 21 in Scolopen- 

 dridae, and from 30-173 in the 

 Geophilidae. In the last-named 

 family the number varies in different 

 individuals of the same species. The 

 number of leg-pairs is always un- 

 equal. The constitution of the head, 

 in comparison with that of other 

 Tracheates, is given in the table on 

 p. 325 in the column for Myriapoda. 



The antennae, which are usually set far apart, but in the 

 Geophilidae are approximated, consist of from 12 to over 100 

 joints (when over 70 the segments are indistinct). Speaking 

 generally their length may be said to vary inversely with that 

 of the body. The eyes are ocelli : they are placed on the sides 

 of the head behind the antennae and may be numerous or few or 

 reduced to one pair (Henicops, and Cermatobius) or absent 

 (Geophilidae , Cryptops, etc.) . In Scutigera there is one pair of com- 

 pound eyes. The labrum (Fig. 358, Ob] is either free or fused with 

 the anterior and ventral part (lamina frontalis) of the cephalite. 

 The mandibles (Fig. 358, md), which may present a division 



FIG. 357. Lithobius jorficatus (after 

 C. L. Koch). Kf poison claws 

 (maxillipeds). 



