From CHILI we hear of the execution, at Valparaiso, on the 4th of April, of Cambiaso, the brigand leader of the convict insurrection at the Straits of Magellan, together with six of his accomplices. They all belonged to the army, Cambiaso being a lieutenant, and were stationed at the garrison. The insurrection which he headed resulted in the seizure of two American vessels, and the murder of all on board. Several others connected with him were convicted, but pardoned on proof that they had been forced to join him. From RIO JANEIRO the only news of interest, is that of the ravages of the yellow-fever, which has been very severe, especially among the shipping. At the middle of April, there were great numbers of American ships in port, unable to muster hands enough to get out of port. In PERU the Government has issued a decree against Gen. Flores's expedition, dated the 14th of March, and stated that having received repeated information of the warlike preparations taking place in Peru, they have ordered the Prefects of the different provinces to take all possible measures to put a stop to them; that government will not afford protection to any Peruvian citizen who should embark on this expedition, or take any part in it, and that all Peruvian vessels engaged in the expedition, would no longer be considered as bearing the national flag. From NEW GRENADA we learn that the President has issued a Message concerning the Flores expedition against Ecuador. From this it appears that, according to a treaty of peace, amity, and alliance, established between the Government and that of Ecuador, in December, 1832, the one power is at all times bound to render aid to the other, both military and pecuniary, in case of foreign invasion. To this end, the President has proclaimed that there be raised in this country, either by loan or force, the sum of sixteen millions of reals, or two millions dollars; and further, that twenty thousand men be called to serve under arms, in order to assist the sister republic. The President declares his intention to oppose Flores and all countries rendering him aid, and accuses Peru of fitting out two vessels, and Valparaiso one, to assist in his expedition; he also demands authority to confiscate the property of all natives and foreigners residing in New Grenada, who may be found to have aided or abetted Flores in any way in his present revolutionary movement. He further states his belief that Flores is merely endeavoring to carry out his revolutionary movement of 1846, in which he was defeated by the British Government, and that the object of the present revolution is to re-establish a monarchical government on the South Pacific coast, under the old Spanish rule. He also expresses his fears that Flores, if successful in Ecuador, will immediately come into New Grenada, and therefore deems it not only a matter of honor, but also of policy, to assist Ecuador. Among the documents submitted, is an official letter to the Ecuadorian