178 MR. H. a. SEELET ON OSSEOUS RESEMBLANCES 



plan seen in the Elephant. The pubis is proportionally larger 

 than in any mammal, the expanded flattened bones of Chelo- 

 nians diff"ering in having a mesial angular prolongation forward, 

 of which there is a faint indication in the Camel, but which, 

 if transversely truncated and ossified separately, would have 

 made prepubie bones after the pattern of those seen in the Mouo- 

 tremes. External to this is a strong digit-like process directed 

 outward, of which only a faint trace is seen in JEchidna. In the 

 marine Chelonia the pubis is much larger than the ischium, which 

 bone, as well as the ilium, is small, the ischium being a simple 

 flattened dicebox-shaped bone. 



The femur has much the proportion seen in the Sea-otter (JEn- 

 hydrd), and is mammal-like in its hemispherical articular head. 

 The great trochanter is rather less developed than in most mam- 

 mals. The obturator pit is moderate ; but, the inner lesser tro- 

 chanter being prolonged up the bone almost as far as the great 

 trochanter, the proximal end has a character unlike that of any 

 mammal's. The distal end, expanded from side to side, is not more 

 thickened from before backward than in the Walrus and Seal ; in 

 those animals, however, the shaft is not cylindrical, and the arti- 

 culation is deeply divided into two parts- 

 There is no patella. The tibia in old Testudines is a massive 

 bone, with almost the heavy proportions of the tibia in a Rhino- 

 ceros. It wants, however, the cnemial crest, of which all mam- 

 mals have some indication at the proximal end in front. In the form 

 of the distal end it approximates to that of mammals, being inter- 

 mediate between that in the Kangaroo and the usual placental type. 

 The proximal end is not expanded so much from front to back 

 as in most mammals ; but the articulation has two ill-defined 

 facets for the femur. 



The fibula is relatively, stronger than in the Ehinoceros, and 

 diff'ers from most mammals' in its cylindrical shaft, and in articu- 

 lating proximally with the femur. Distally it articulates with 

 the OS calcis, as in Marsupials and, it may be, some Carnivores. 



The tarsus consists, as in mammals, of two rows of bones, but 

 wants the naviculare, and differs, moreover, in having the astra- 

 galus and OS calcis anchylosed together side by side, so that 

 neither bone has the characteristic mammalian characters. 



In the Testudine hind foot there are four digits. The metacar- 

 pals are short, obliquely overlap each other at their proximal ends?, 

 and are expanded from side to side distally, shorter and stronger 



