MYRIAPODA. 517 



in Glomeris and Sphaerotherium (Diplopoda}, beset with short glandular 

 tubules, and a short proctodaeum. The anus is terminal, and in Diplopoda 

 is inclosed between two valves borne by the last somite. There is a 

 dorsal heart composed of a series of chambers (two to each somite in 

 Diplopoda}, with valved lateral ostia and inclosed in a pericardial sinus 

 formed by a horizontal membrane, and furnished with alary muscles as 

 in Insecta. Each chamber gives off one pair, or in Diplopoda two pairs, 

 of lateral arteries. There is an anterior aorta which sends forward a 

 cephalic vessel, and two lateral vessels which form an oesophageal ring 

 and unite ventrally into a vessel which lies dorsally to the nerve cord 

 and runs backwards. A single pair of stigmata opens in the pleural 

 membrane of all or certain somites in Chilopoda, with the exception of 

 the genus Scutigera, which has a single median dorsal stigma to each 

 somite. In the Diplopoda, on the contrary, each somite carries two 

 pairs of stigmata, opening ventrally, one at the base of each pair of limbs ; 

 but in Glomeris the three first pairs of stigmata belong each to a separate 

 somite. The stigma in Diplopoda and in Scutigera leads into a chamber 

 or ' tracheal sac/ from which originate bundles of simple tracheal tubes. 

 Glomeris, however, is an exception. Each of its tracheal sacs gives origin 

 to two branching trunks. Large tracheae, which branch and anastomose 

 both longitudinally and transversely, arise from each stigma in Chilopoda 

 a group in which the lining cuticle and spiral line are well marked. It 

 is possible that ti\t Archipolypoda possessed a pair of branchial appendages, 

 situated ventrally on each somite. A single pair of urinary or Malpighian 

 tubes opens into the proctodaeum in Diplopoda, two pairs in Chilopoda. 



The sexes are separate. The ovary is generally a single tube, rarely 

 double as in Craspedosoma (Diplopoda}. There are two oviducts in Diplopoda, 

 one or two in Chilopoda. Cement glands and receptacula seminis open 

 either into the oviduct itself or, as is more usual, into the genital orifice. 

 The testis also may be a single tube, or as in some Diplopoda (certain 

 Glomeridae and lulidae] two tubes connected by transverse anastomoses. 

 The vasa deferentia, like the oviducts, may be single or double, and are 

 always provided with accessory glands. In Diplopoda the two genital 

 apertures are in connection with the basal joint of the second or third 

 pairs of limbs. In Chilopoda there is a single posterior aperture, fuhtshas 

 a copulatory organ on the seventh post-cephalic somite ; Sphaerotherizim 

 three pairs of copulatory appendages between the last pair of ambulatory 

 limbs and the anus ; and the corresponding organs in Glomeris are similarly 

 placed. The Scolopendridae possess a short penis. Scolopendra is vivi- 

 parous, other Myriapoda lay their eggs in earth, &c. The young Paurcpus 

 is hexapodous, so too Lithobius 1 . Some of the Diplopoda have an 

 hexapodous stage, in which however the three pairs of limbs are not on 



1 Haase states, however, that it has eight limb-bearing somites. 



