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



importance of its appendages, which are large, three-jointed and palpiform, 

 and seem to represent the external or maxillary palpi of Insects. They are 

 situated one on each side of what has heretofore been described as the internal 

 labium, but which, I conceive, may be regarded as the lingua. This struc- 

 ture, which is well seen in Scolopendra (fig. 7^, is formed of two elongated^ 

 delicate plates {c,c), situated between the palpi, and forming the floor of the 

 entrance to the pharynx, which they close in below. They seem to be the 

 proper episternal portions of this segment of the head. 



Although these subsegments are all clearly indicated in the perfect state of 

 Arthronomalus {Geophilus) longicomis, Leach, some of them only are distin- 

 guishable in other species, as in the true Geophili (fig. 10.) and Gonibregmati 

 (fig. 4.), in which the head has assumed a more compact form, and the antennal 

 subsegment is alone distinguished ; while all trace of the divisions is entirely 

 obliterated in the narrowed and elongated cephalic segment oi Mecistocephalus 

 (fig. 18.). In Cryptops (fig. 20.) and Scolopendra (fig. 4.) there is an indication 

 of the extent of the antennal subsegment, but, as in Geophilus, an entire ob- 

 literation of the others. Tliis also is the case in Lithobius (fig. 27 and 29.), 

 in which the boundary of the antennal segment is marked by a deep curved 

 suture. In Cermatia (fig. 36.) the whole cephalic region has assumed a new 

 form ; the antennal and optic segments being now extensively developed, and 

 occupying the larger portion of the head, and the organs of vision have en- 

 croached backwards on the third subsegment. 



The four subsegments that form the posterior part of the head are more 

 slowly united in the basilar region. In Geophilus this union is only com- 

 menced. The Jifth and sixth segments of the young animal, each, as we 

 shall presently see, developing a pair of large appendages, unite at a much 

 later period than the cephalic subsegments. The fifth unites with the sixth, 

 but not until the primary divisions of its appendages are modelled, and not 

 without leaving a portion of its dorsal surface attached to the sixth, indicating 

 its original separation. This is most distinctly shown in Mecistocephalus 

 (fig. 17 and 18.), in which it remains as a small quadrangular plate (5.). It 

 exists also in Scolopendra in the form of a raised lunated fold, on the anterior 

 margin of the great basilar segment (fig. 4, b). But in the higher genera this 

 also has disappeared. 



