vi ANTENNATA TRUNK LIMBS 453 



the 4 or 5 anterior rings are only provided with 1 pair each. 

 One of the 4 or 5 anterior rings in the lulidce it seems to be the 4th 

 may be limbless. The extremities of the 7th ring are usually trans- 

 formed in the male into copulatory organs. 



/ 

 Rudiments of abdominal limbs in the Hexapoda. 



In order to prove the existence of such rudiments we must recall the coxal glands 

 emerging on the legs of Peripatus. Similar glands emerge in the GMlopoda on the 

 coxae of the 4 or 5 last pairs of legs, on the pleura of the last leg-bearing segment, and 

 on the anal segment. In the Diplopoda these glands apparently correspond with 

 the protrusible warts which occur in the Lysiopetalidce on the coxal joints of the 3d- 

 16th pairs of legs, and also with the pores on the coxae of the Chordeumidce. A 

 knowledge of these organs in the Symphyla (Scolopendrella), which perhaps of all 

 living Antennata stands nearest the common racial form of the Myriapoda and the 



FIG. 313. Posterior end of body of Scolopendrella immaculata, from the ventral side (after 

 Latzel). pu llth, pi z 12th undeveloped, pairs of legs, p 13 , transformed legs (13th pair) carrying 

 organs of touch (so) ; sg, spinning processes with the duct (dg) of the spinning gland ; cd, coxal 

 gland : hs, coxal spur of the llth pair of legs. 



Insecta, is extremely important. On the coxal joints of the legs in Scolopendrella 

 protrusible saccules, apparently glandular (Fig. 313, cd), can be distinctly made out, 

 especially on the 3d-llth pairs. Laterally from these saccules, which must be homo- 

 logous with the coxal glands of other Myriapoda and of Peripatus, there is a stylet- 

 shaped appendage hs, which must be considered as a modified process of the coxal 

 joint (coxal spur). In addition to these coxal saccules, Scolopendrella possesses 2 spin- 

 ning glands, which emerge externally (dg) at the point of the spinning processes (sg), 

 on the terminal segment of the body. These glands also probably belong to the 

 category of coxal glands, and thus the spinning processes probably represent the last 

 pair of limbs considerably transformed. The coxal saccules of Scolopendrella and 

 the coxal glands of the Myriapoda and Protracheata (Peripatus) now throw much light 

 on similar arrangements in the lowest Hexapoda, the Apterygota. In Campodea there 

 are in the first abdominal segment two indistinctly jointed appendages which are 

 rudimentary'extremities. In the subsequent abdominal segments as far as to the 8th 

 there occurs on each side ventrally a protrusible saccule on whose outer side lies a mov- 

 able pointed process. These saccules evidently correspond with the coxal glands of 

 Scolopendrella, and are to be considered as degenerated coxal glands, while the 



