Successive discoveries gradually revealed the world of extinct Reptilia; in 1821 Charles Konig (1784-1851), the first keeper of the mineralogical collection in the British Museum, described Ichthyosaurus from the Jurassic; in the same year William Daniel Conybeare (1787-1857) described Plesiosaurus; and a year later (1822) Mosasaurus; in 1824 William Buckland described the great carnivorous dinosaur Megalosaurus; while Gideon Algernon Mantell (1790--1852) in 1848 announced the discovery of Iguanodon.
His successor was the duke of Connaught and Strathearn; the vice-presidents including the duke of Portland, Lord Algernon Gordon Lennox, J.
The popularity of Charles, now greatly increased, was raised to national enthusiasm by the discovery of the Rye House plot in 1683, said to be a scheme to assassinate Charles and James at an isolated house on the high road near Hoddesdon in Hertfordshire as they returned from Newmarket to London, among those implicated being Algernon Sidney, Lord Russell and Monmouth, the two former paying the death penalty and Monmouth being finally banished to the Hague.
Sir Algernon West was elected to the chair, and ultimately two main reports were presented, one section agreeing with Lord Peel, and the other - including the majority of the commissioners - presenting a report which differed from his in several important respects.
Northumberland House, from which is named Northumberland Avenue, opening upon Trafalgar Square, was built c. 1605 by Henry Howard, earl of Northampton, and was acquired by marriage by Algernon Percy, earl of Northumberland, in 1642.