JVo.4.] SHUFELDT ON THE OSTEOLOGY OF SPEOTYTO. 115 



the larger part of the shaft in regard to size. Below the ridge this bone 

 becomes simply a delicate little spine, that merges into the shaft of the 

 tibia at about the junction of middle and distal thirds, though it may 

 be traced after this as far as the middle of the outer condyle, where it 

 terminates by a minute tubercle. The head is notched externally, near 

 the centre, and hp,s lodged at that point a small sesamoid that is in the 

 lateral ligament of the knee-joint. Posteriorly on the shaft, about midway 

 ilown the superior tibio-fibular anchylosis, we observe a small tubercle 

 for the insertion of the tendon of the biceps. The long segment that 

 exists between the tibia and the x>halanges of the pelvic limb is the bone 

 tarso-metatarsus, or the confluent metatarsals of the second, third, and 

 fourth toes with certain tarsal bones at its i)roximal extremity. It meas- 

 ures down the anterior aspect, mesially, 4.6 centimetres, and has its ex- 

 tremities enlarged for articular purposes, in common with other long bones 

 of the skeleton. At its proximal end the bone presents superiorly two con- 

 cave articular surfaces for the condyles of the tibia. They appear nearly 

 on a level with each other, the bone being held vertically. The inner and 

 larger of the two is elliptical in outline, antero-posteriorly j the outer and 

 smaller is fashioned oft' behind by a tuberous process, directed upwards 

 and outwards. Between these two surfaces arises a prominent tuber- 

 osity, that in the articulated limb enters the intercondyloid notch of the 

 tibia quite accurately, and is intended for ligamentous attachment. An- 

 teriorly and internally a groove exists that runs down the shaft, to dis- 

 a^ppear a little above its middle. This canal is deepest immediately be- 

 low the articular expansion, and is here bridged over by a little arch of 

 bone, a millimetre in width, that serves to bind down and hold in its 

 proper place the tendon of the long extensor of the toes. Posteriorly 

 there is a much deeper and longer tendinal canal, that extends the entire 

 length of the shaft, being shallowest at the middle and most capacious 

 at the proximal extremity j this is bounded over and internally for a 

 short distance below the head of the bone by the calcaneal process, a 

 thin lamina of bone that has a foramen near its base ; this process is 

 surmounted by an elliptical and compressed tuberosity, placed vertically. 

 The opposite wall, above, of this groove is also thin, and extends, in 

 common with the calcaneal process, directly backwards. There are two 

 other foramina seen at this end of the tarso-metatarsus ; one just at the 

 external termination of the bony bridge mentioned above, and the other 

 outside and a little above it. Their posterior openings are immediately 

 behind the anterior ones, or, in other words, they do not pierce the shaft 

 in any way obliquely. The shaft of this bone is notably square on sec- 

 tion for the major part of its extent, being encroached upon, however, 

 both before and behind, by the aforesaid tendinal grooves. The tendons, 

 especially those that occupy the posterior canal, are very prone to ossi- 

 fication, forming quite sizable bones in the adult, the largest of these 

 being equal to the fibula in bulk, exclusive of coiu-se of the head of that 

 bone, and not being as long. Keturning to the tarso-metatarsus, we find 



