18G ANATOMY OF VERTEBRATES. 



A slight modification is presented by Trionyx, in which a view 

 of the pelvis is given from the dorsal aspect, the sacrum being 

 removed, in fig. 116 : here i shows the end of the ilium, 62, which 

 was attached to that part of the vertebral column : a is the ex- 

 panded acetabular end of these short, straight, columnar bones. 



116 



/I 



Pelvis of Trionyx, (.from above, without the sacrum). CM. 



The ischia, c, c, develope tuberosities f, f, and unite at the ischial 

 symphysis, 64, d. The pubics b, b, articulate by a broader tube- 

 rosity, h, with the plastron, and have a greater transverse extent. 

 The ' outlet ' of the pelvis is not, as might be supposed, between e 

 and 64, but between i and/. The wider space answers to the ob- 

 turatorial one in Man ; and, were ossification to be extended from 

 the ischial, 64, to the pubic, e , symphysis, it would be divided into 

 the two vacuities called ' foramina ovalia seu obturatoria ' in the 

 human pelvis. Such division does actually take place in the 

 Tortoises (Teshido) and Terrapenes, as shown at v, fig. 51, in 

 Emys Europoea. 



In the Tortoise (Testudo) the iliac bones are vertical and 

 columnar, like the scapula, but are shorter and more compressed. 

 The pubis expands to join its fellow at the median symphysis and 

 the ischium posteriorly : it sends outward and downward a long 

 thick obtuse process from its anterior margin. The ischia, in like 

 manner, expand where they unite together to prolong the sym- 

 physis backward. The ' foramen ovale seu thyroideum ' is nearly 

 circular on each side. In Hydraspis the ilia articulate directly by 

 part of their under surface to the xiphisternals, and the pubis 

 becomes confluent with the same parts of the plastron by the 

 tuberous process. 



The femur is shorter than the humerus in the Turtles : the head 

 is round, surmounted by a broad, thick, short trochanter : the 



