A NEW AND ANXKCTANT TYPE OE CHILOPOD. 443 



requiriug serpentine powers of movement. To further subserve 

 this end, most of the somites are either pai'tially or completely 

 divided into two anteriorly, a process which, when perfected, 

 gives rise to a series of sub-segments alternating with the 

 true somites, the former being represented by a pra^tergal 

 and a pair of prsesternal plates. Stigmata are retained on 

 all the somites, except tlie first and last, for purposes of 

 respiration under ground ; and the legs, which are short and 

 play but a subsidiary part in locomotion, preserve the primi- 

 tive number of segments, the basal of which remains small. 



The eyes, as useless organs, have disappeared; and the 

 autennee are relatively short and consist invariably of fourteen 

 segments. The gnathites are specialised and variable in struc- 

 ture; the penultimate and antepenultimate segments of the 

 toxicognaths are reduced on the prasaxial side of the appen- 

 dasfe to the state of arthrodial inteorumental folds between the 

 distal segment and the femur, which are firmly articulated 

 together on its post-axial side. The tergal plate of these 

 appendages always remains distinct and usually large, thus 

 separating the cephalitc from the tergum of the first leg- 

 bearing somite. The pleural sclerites are well developed, 

 and those of the last leg-bearing somite fuse with the coxa 

 of the appendage, the second segment of which remains free. 

 The anal and genital somites are incapable of retraction within 

 the somite which bears the last pair of legs, and the gonopods 

 typically persist in the male as small-jointed appendages, and 

 in the female also as jointed or unjointed, often lobate sclerites. 



Many families — Geophilidte, Oryidse, Clonibregmatidaj, etc. 



Order 2. — IS colopeudromorpha. 

 Chilopods departing from the primitive type and from the 

 Geophilomorpha in having the number of leg-bearing somites 

 fixed definitely to twenty-three or twenty -one, the reduction 

 in number in the latter case being effected by the escalation 

 of the two somites preceding that which bears the last pair 

 of legs; by the evanescence of the tergal plate of the toxico- 

 gnaths, which results in contact between the cephaliteand the 



