74 BOLKAY 



The diapophysis of the eighth vertebra (fig. 8) generally curves 

 backwards, median side also expanding wing-like backwards. 



It is worth mentioning that the processi spinosi of the vertebrae 

 are longer on R. chinensis than on either R. esculenta or R. ridibunda. 

 If we join, by a straight line, the back borders of the processi obliqui 

 on the second, third and fourth vertebras we shall find that the 

 processi spinosi invariably extend beyond this line. On R. escu- 

 lenta and R. ridibunda the processi spinosi generally touch that line, 

 sometimes ending a good deal before it. 



The urostylus is as long as the vertebral column. 



If we examine the pelvis (fig. 9) so that the symmetric plane 

 passing through the symphysis is parallel with the base we will 

 find the following peculiarities: pelvis 1. 2-1.3 times as long as the 

 vertebral column; ilium in its general form straight, the extremities 

 touching the sacral vertebra, being alone slightly curved downwards; 

 upper ridge of the ilium's crest straight and the angle of it which 

 declines towards the acetabulum forms only just a somewhat larger 

 angle than a rectangle. This declining angle is smooth, or presents 

 a hardly visible distended margin ; if we draw on the ridge of the 

 ilium crest a line parallel to the base of the pelvis, this fine will 

 just be reached by the upper corner of the crista ischio-pubica. 



In R. esculenta (fig. 10) the pelvis is 1. 06-1. 2 times as long as the 

 vertebral column; the ilium is curved, the upper ridge of its crest 

 is rounded and the corner declining towards the acetabulum forms 

 a very blunt angle. This declining corner presents a strongly 

 distended margin and consequently under this margin at the base 

 of the ilium we find a somewhat deep cavity; if we draw on the ridge 

 of the ilium crest, a line parallel to the base of the pelvis, we shall 

 notice that the upper corner of the crista ischio-pubica remains far 

 under that line. 



The most interesting of the tarsus bones is the so-called praehallux 

 (fig. n) which is a large, flat spade-like bony plate, growing rather 

 thick towards its base; its outer surface somewhat convex, whilst 

 the inner one is very slightly concave; its greatest breadth equal to 

 two-thirds of its length, the latter to two-thirds to three-fourths 

 of the length of first meta-tarsal bone. In R. esculenta the praehallux 

 (fig. 12) is a flat, thin bone plate; greatest breadth half its length, 

 length half that of the first meta-tarsal bone. 



