828 Transactions of the Society. 



of the thorax below the limbs is expanded into a hoodlike carapace 

 ( = omostegite of Huxley), which is small and attached all ronnd to 

 the body in the male (Fig. 1, m), but large and open below in the 

 female (Figs. 5 and 6 in section). The abdomen (Fig. 1, o), 

 (Fig. 2, 1-4), consists of four somites of unequal length, but 

 nearly the same width ; the terminal one is divided at the end into 

 two long sickle-shaped hooks (Figs. 7 and 4, u) covered with short 

 flat spines, a row of larger ones along the inner edge. 



II. The Digestive and Circulatory System. 



The alimentary apparatus of Lejotodora is very simple. The 

 mouth I have already described. The bases of the mandibles 

 (Fig. 1, ji") are embedded in a muscular bulb in the thorax, but the 

 points are free and project into the mouth, one on each side, at the 

 junction of the upper and lower hps. Their points are armed 

 with three or four projecting teeth (Fig. 10). Whenever the 

 mouth opens these mandibles begin to work towards each other 

 across the opening of the oesophagus, tearing the food as it passes 

 between them. The food consists chiefly of small water insects 

 and other living things. The pharynx (Fig. 1, </) is not always 

 open, and I have seen it opening and shutting as if it were closed 

 by a sphincter muscle. It passes straight backwards as far as the 

 roots of the mandibles, and is surrounded by a number of cells, 

 which are probably salivary glands. It passes between the man- 

 dibles and then curves suddenly downwards, and enters the oeso- 

 phagus, a long tube traversing the centre of the abdomen as far as 

 the last somite but one, where it is expanded into a stomach the 

 walls of which are corrugated interiorly. The anus is situated be- 

 tween the terminal hooks, at the end of a short rectum (Fig. 2, s). 



On each side of the heart there is a long dark vessel (Figs. 1 

 and 2, n), which is probably a kidney. It is bathed all round 

 with the blood, and would no doubt secrete the urine from it as it 

 passes. It is divided at the end into two lobes, one of which is of 

 a darker colour than the other. A long duct leads from it 

 upwards into the centre of the thorax, where it gets lost in the mass 

 of muscles and nerves which crowd this part, so that I have not 

 been able to trace them any further. I think, however, that the 

 ducts enter the oesophagus, and their contents then find their way 

 out through the same opening as the other faecal matters. 



There is no trace of a hver, but probably the walls of the 

 stomach secrete some fluid analogous to the gastric juice. The 

 circulatory system is also very rudimentary. The heart (Fig. 1, /, 

 Fig. 2, ly and Fig. 12) is a perfectly transparent sac encircled with 

 numerous muscles, situated in the centre of the thorax, to the sides 



