598 CLASS III. MYB1APODA. 



rectum has an S-shaped curvature ; in Lithobius the oesophagus 

 is short and the rectum is straight. 



A number of glands, which may be called salivary, open in 

 connexion with the mouth. In Scolopendra and Scutigera there 

 are five pairs, in the Lithobiidae two or three pairs. The 

 posterior of these open on the coxae of the first pair of legs and 

 are coxal glands. In Scolopendra the two anterior pairs are 

 contained in the head and open within the labrum into the 

 buccal cavity. The two posterior pairs are much larger and 

 extend from the 3rd to the 7th body-segment. Their ducts have 

 a spiral fibre and open into the mouth in front of the 2nd maxillae. 



The central nervous system consists of a bilobed cerebral 

 ganglion (p. 328) in the head, supplying the antennae, the eyes, 

 and organs of Tomosvary ; of a suboesophageal ganglion which 

 supplies the jaws and the maxillipeds (the ganglion of the latter 

 is distinct in the embryo), and of a ventral chain of ganglia, 

 one of which occurs in each pedigerous segment. The ganglia 

 of the first and second pedigerous segment are approximated. 

 Behind the last there is a genital ganglion. The cerebral ganglion 

 gives off a visceral nerve to the dorsal wall of the gut. 



Vascular system.* The heart (Fig. 359), which is contained 

 in the pericardium, extends nearly the whole length of the body 

 from the first pedigerous segment backwards. It possesses a 

 pair of ostia and gives off a pair of arteries in each segment, 

 and in front it is continued as an artery to the cephalic organs. 

 The arteries branch and finally end by opening into spaces in 

 the connective tissue. Some of them terminate in small bodies 

 resembling lymphatic glands (Kowalevsky's bodies). There is 

 also a supraneural vessel lying along the dorsal side of the nerve 

 cord and directly connected with the front end of the heart 

 by a air of arterial arches which embrace the gut. The peri- 

 visceral and pericardial cavities communicate by perforations 

 in the pericardial membrane, and there are alary muscles in the 

 floor of the pericardium. In spite of the peculiar local breathing 

 organs of Scutigera the blood system in that animal is not 

 essentially different from that of Scolopendra. The blood is 

 colourless, but in Lithobius it is stated to have a slight violet tinge. 



* G. Newport, Phil. Trans., 1843. C. Herbst, Bibl. Zool. (Chun and 

 Leuckart), Heft 9, 1901. O. Duboscq, Arch. Zool. Exper. (3), (>, 1897, 

 p. 481. 



