ORDER MYRIAPODA. 127 



ing them as a common basis ; the feet very short, and ter- 

 minated by a single crotchet ; four feet situated immediately 

 under the preceding piece, of the form of those which 

 follow, but approximating more to their basis, with the 

 radical articulation proportionately longer, and the majority 

 of the others attached in double pairs to a single ring. The 

 male genital organs are situated immediately after the 

 seventh pair of feet, and those of the other sex behind the 

 second. The stigmata are placed alternately, outside the 

 origin of each pair of feet, and very small. 



The chilognatha walk very slowly, or slide along, as it 

 were, and roll themselves up into a spiral or ball. The 

 first segment of the body (and in some the following one) 

 is the largest, and presents the form of a corslet or small 

 buckle. It is seldom until the fourth in some, and the fifth 

 or sixth in others, that the duplicature of the pairs of feet 

 commences ; the first two or four feet are even entirely free 

 as far as their origin, when they adhere to their respective 

 segments, only by a medial or sternal line. The last two or 

 three rings are apodal ; on each side of the body is seen a 

 series of pores, which have been taken for stigmata, but 

 which, according M. Savi, are destined for the issue of a 

 sort of acid liquor, and of a disagreeable odour, which seems 

 to serve as a defence against enemies. The apertures proper 

 to respiration, the discovery of which is owing to him, are 

 placed on the sternal piece of each segment, and commu- 

 nicate interiorly, with a double series of pneumatic pouches, 

 arranged like chaplets all along the body, and from which 

 proceed the tracheal branches, which spread themselves over 

 the other organs. According to the observation of M. Straus, 

 the pouches or vesicular tracheal, are not connected one with 

 the other in the ordinary way by a principal trachea. 



In the environs of Pisa, where M. Savi collected the fore- 

 going observations, the season of reproduction with the com- 



