286 Proceedings of the Royal Institution. 
Prop. 2. El. b. vi. as far as itextends to commensurable lines. The 
three lines drawn from the angles of a triangle to the middle points 
of the opposite sides have a common point of intersection. Also, 
the three lines bisecting the angles of a triangle. Prop. 47, 48. El. 
Pappus’s Theorem. Prop. 12, 13. El. b. ii. 
Monday, June 14, § vy. Problems. 
Sy.iasus or a Course or Lectures on ZOOLOGY, COMPRE= 
HENDING A SURVEY OF THE CLass Mammatia. By J. Har- 
woop, M.D., F.L,S., &c. 
Lecture I. Wednesday, April 28. 
Introductory Observations. Necessity of systematic arrangement 
in the study of Animated Beings. The bony fabric in Quadrupeds. 
Division of the Mammalia. 
Order Ist. The Ape tribes, or Quadrumana; their curious adap- 
tation in form and structure to their natural habits and economy. 
The Ourang Outang. Peculiarities in form, character and manners 
in African Monkeys. Baboons, American species, Lemurs. Ga- 
lago, &c. 
Order 2d. The Beasts of Prey or Carnivora; their diversity in 
form and habits; perfection of their senses; relative powers of 
destruction; modes of attack. The Bats. Other insectivorous 
Quadrupeds. 
Lecture II. Wednesday, May 5. 
Carnivorous Animals continued, Bears. Dogs. Hyenas. Feline 
tribes. Geographical distribution of species. Amphibious Qua- 
drupeds. Seals. Walruses, &c. Extinct fossil species of the Car- 
nivora. Caves in Germany containing them. Manner in which 
their remains are deposited. Kirkdale Cave. 
Order 3d. The Gnawing Animals, or Rodentia. Peculiarities in 
the formation and habits of the principal genera. 
Lecture HII. Wednesday, May 12. 
Order 4th. The Edentata. Remarkable formations and economy 
in the Sloths, Anteatus, Armadillos. Gigantic fossil species resem- 
bling the Sloth. 
