Mr. Newport on the Class Myriapoda, Order Chilopoda. 375 



shaped, and narrowed anteriorly, with its posterior margin thin and rounded, 

 or straight and abbreviated. The antennae are tapering, with from seventeen 

 to twenty slightly elongated, subcorneal joints. The basilar segment (b) bears 

 the large mandibles, and also the first pair of legs, which are atrophied and 

 palpiform. The segments of the body are alternately longer and shorter on 

 the dorsal surface, but nearly equal on the ventral ; and there are usually 

 nine, but in some genera ten pairs of spiracles at the sides (a, b). The poste- 

 rior pair of legs are elongated, and their basilar or femoral joints are in gene- 

 ral armed with strong spines. 



The generic characters of the family are derived in part from the number 

 of legs and spiracles, and joints in the antennae, and from the organs of vision. 

 The latter consist of four stemmata on each side (Tab. XXXIII. fig. 35.) in 

 Scolopendra, Heterostoma, Cormocephalus and Scolopendropsis, but in Cryptops 

 they are either entirely absent, or consist but of a single ocellus concealed 

 beneath the under surface of the head (24*). 



The structural characters of species are derived from the denticulations of the 

 labium (fig. Sf.) and from the number, arrangement and shape of the spines, 

 and the form of the femoral joints of the posterior pair of legs (Tab. XXXIII. 

 fig. 22. s. and Tab. XL. fig. 5. to 10.). Professor Brandt has correctly remarked, 

 that the shape and armature of the posterior legs usually afford good characters, 

 as the peculiarities of these parts are as constant in the young as in adult speci- 

 mens. This is always the case, except in those instances in which the limbs 

 have been reproduced, and then very frequently some of the spines are absent ; 

 while in other instances of reproduction the spines are smaller and more nu- 

 merous than in the original limbs. The similarity of the structural characters 

 in the young and adult individuals arises from the circumstance that the Chi- 

 lopoda acquire the whole of their segments, legs, ocelli, and joints to the an- 

 tennae, before they have attained even one-third of their adult size ; so that, 

 although they continue to undergo repeated changes of tegument, they then 

 merely increase in bulk and length at each change. The number of joints to 

 the antennae may be employed in the division of the Scolopendrce into sections, 

 which hereafter, perhaps, maybe found sufficiently uniform to constitute sepa- 

 rate genera. But this character is of no use in the identification of species. 

 Thus an elongated form of the posterior pair of legs, armed with three spines 



VOIi. XIX. 3 D 



