Fresh alarm was caused here this morning by the discovery that our telegraphic communication has been interrupted at once with Odessa and with Batoum. All inquiries as to the cause of the rupture made by other routes failed to elicit any explanation. Later in the day a vessel of the Cunard line arrived in the Bosphorus, and her captain has stated that the Russian harbour-master at Odessa is detaining all ships, of whatever nationality, in that port. His own vessel, he says, was the last to leave Odessa, and only got away by a chance, the order having reached him when he had already got under way. He states that there were several Russian ironclads, and quite a fleet of torpedo boats at Odessa, all with steam up, and says that when he was on shore there the day before yesterday the town was full of soldiers, and the approaches to the dockyards crowded with a constantly-increasing mass of guns, horses, ammunition, and other war material. CONSTANTINOPLE, _April 18_. I have received a telegram from my correspondent in Sofia, who tells me that the Bulgarian Government understands that the Russians are preparing an expedition for sea at Odessa, and intend to occupy some portion of Bulgarian territory. The Princely Government has reason to expect the attack will be directed against Varna, and has called upon the Sultan to aid Bulgarian arms by sending his fleet to guard the Varna roads. The Sultan has as yet made no reply to this request, says my correspondent, but it is not difficult to guess what His Majesty’s action will be, inasmuch as Turkey has no single ship of war in condition to be got to sea under a month at the least, and it is more than questionable whether even then any of the ironclads could be completely manned or provided with serviceable ammunition. There are, indeed, some torpedo boats—unprovided, I understand, with torpedoes—and a couple of the monitors that did some service in the Danube in the last war. If the Admiralty should elect to place these vessels at the service of the Bulgarian Government, they might be of some use as scouts. But that is about all that Turkey can hope to do for her vassal. [Illustration: WITH THE TURKS: ADMIRAL WOODS PACHA’S FLEET OF TORPEDO BOATS STEAMING THROUGH THE BOSPHORUS. ] Here there is terrible anxiety lest the Russian expedition be directed, not against Varna or Bourgas, but against the Kavaks, and the Seraskierate is busily taking precautions to meet such a contingency with all the forces available.