534 TRANSACTIONS OF SECTION D. 
seem at first to have adopted a simpler plan, that comes somewhat within the 
domain of the working physicist. The adoption of different means of movement 
has led to complication. The use of the third and fourth toe in progressing, of 
the fourth especially in such forms as galago and other lemurs, and the special 
changes in the wrist and ankle bones have led to changes in the form, length, and 
strength of bones. The weight of the animal has often been a potent factor in 
modifying bone and limb. The relative thickness of the humerus and femur at 
the narrowest parts in mammals shows how much the weight of the animal or its 
parts and the activity of muscles avail in accomplishing work. The same holds 
with reference to certain other heavy headed varieties of ungulates. Thus the 
humerus of the elephant is of greater girth than that of the femur. It has less 
girth in the horse, and the girth is about equal in some breeds of domestic cattle. 
The forearm and the leg bones follow the same rule. 
The smallest circumference of the humerus and femur are for the following 
animals measured :— 
ro 1s, Cervus Equus Equus Camelus 
aoe Capreolus Caballus Asinus Dromedarius 
Humerus . 14 4:0 cm. 13°3 8-6 17:0 cm. 
Femur 14:5 4:5 cm. 6°7 10:0 14°5 cm. 
_ Elephant- Rhinoceros Trish Elk Hippo- Bos 
potamus 
Humerus 23°5 25-2 175 20 11-2 ems. 
Femur, 22:0 25:2 16°5 21 11:2 cms. 
It becomes a question also with reference to the modulus of elasticity of the 
bone, and the modulus of firmness in each case, and also with reference to the 
size of the medullary canal. 
The circumference of the humerus exceeds the least circumference of the 
femur in two buffaloes in the Museum d’Histoire Naturelle, Paris. 
7. The Solutré Type of Horse (E. robustus) in Prehistoric Britain, 
By A. Irvine, D.Sc., B.A. 
A.—Evidence from Teeth. 
1. In the excavation of a watermain trench (33 to 4 feet deep) across the Stort 
Valley in 19127 four teeth of the cheek-dentition have been found identified by 
their shape and by the antero-posterior lengths of their crowns and internal 
pillars respectively) with p.m. 2, p.m. 3, p.m. 4, and m. 3 of the series figured 
by Prof. J. C. Ewart, F.R.S., as of the Solutré type of horse (#7. robustus) in 
his monograph on ‘ The Restoration of an Ancient British Race of Horses.’ ” 
To these may be added a p.m. 4 (Pleistocene) in the Sedgwick Museum (Cam- 
bridge), and the p.m. 4 from Piltdown,* recorded by Woodward and Dawson. 
Others have been identified in the museums of Saffron Walden and Maidstone. 
2. A broken premaxilla retaining four large incisors corresponding by 
measurements with that of a ‘forest’ horse from Walthamstow in the British 
Museum (Nat. Hist.). 
3. A p.m. 3 (identified by Prof. Ewart as of ZH. robustus*) found some 
years ago under 12 feet of Pleistocene gravel at Stanstead Abbots in the Lea 
Valley. 
Of the above (1) and (2) were all found at the bottom of the ‘rubble-drift ’ 
on the old Jand-surface of interglacial sands and Woolwich and Reading Beds, 
which were cut into in the trench. 
1 See Herts and Essex Observer (Mardon, Bishop’s Stortford), for Feb. 8, 
1913. 
2 Proc. R. Soc. Edin., Session 1909-10 (fig. 23). 
3 Q.J.G.S., vol. 69, p. 143; identified later. 
* Now in the St. Albans Museum. 
