The last lecture of the first series of the Star Course was delivered last evening in the Michigan Avenue Baptist Church by Samuel L. Clemens, alias "Mark Twain." The audience was immense, the main auditorium lecture room and Sunday School rooms being all thronged, the aisles all filled with extra seats and scarcely any standing room left. After the usual organic prelude the hero of the hour stalked into the room and mounted the rostrum in a very unheroic manner, and without much modesty or affectation introduced himself. The reminiscences consisted of exploits and discoveries in California. While truly eloquent in his glowing descriptions of California scenery, he was infinitely droll in his yarns of life on the Pacific slope. His endless stories and happy hits kept the audience convulsed with laughter, yet gave much solid information. The lecture is to be repeated this evening in the Union Park Congregational Church, and tomorrow we shall give in these columns a full synopsis of the lecture. The managers of the course now grant a month's vacation to their South Side patrons, the next term opening on the 15th of January with a grand concert by the popular Barnabee Troupe, to be followed by nine literary, scientific, and dramatic "stars."

MARK TWAIN'S LECTURE.--The brilliant and successful conclusion of the South Side Star Lecture Course, on last evening, must have been as gratifying to the managers as it was flattering to "Mark Twain," whose genius drew together one of the largest, and well as one of the most intelligent audiences that have ever gathered in this city to hear a lecture. Over a week ago, nearly all the seats were taken; and it became apparent, that, in order to provide for the crowd that would throng the Michigan Avenue Baptist Church, arrangements more extensive than usual would have to be made. Accordingly, on last evening, the transepts of the church, which open into the main auditorium by means of hanging-doors, were thrown open, thus adding nearly a thousand seats,--every one of which, as well as those in the body of the church, was filled. In the presence of this vast audience, at the appointed time, came strolling on the platform, in the most indifferent and careless manner, the "hero of the hour." As he repeats the lecture to-night on the West Side, and we have been requested to restrain our desire to tell some of the good things he said, so that they will be enjoyed the more by those who have had the good fortune to secure seats, we do not give any detailed report of his lecture.

It consisted chiefly of reminiscences of "roughing it" in California, with accounts of new discoveries in the animal, vegetable, and mineral kingdoms, glowing descriptions of exquisite scenery, droll yarns of life in the bush, which convulsed the audience with laughter during the entire evening. Nothing could have been more quaint than the unconscious manner in which he related his stories, and the half-surprised look he assumes when his audience laughs at some of the serious things he says.

The entertainment of the season, thus far, was the curious, disjointed, delightful talk of Mark Twain (Clemens is his married name), last evening, in the Michigan Avenue Baptist Church, below Twenty-second Street.

Every seat in the house, four hundred chairs in the aisles, and standing-room for two or three hundred, were crowded full, when the lank, lantern-jawed, and impudent Californian bestrode the stage as if it were the deck of a steam-boat, and, getting to the middle of the front, rubbed his bony hands, and gazed around. A thin man of five feet ten, thirty-five, or so, eyes that penetrate like a new gimlet, nasal prow projected and pendulous, carrotty, curly hair, and mustache, arms that are always in the way, expression dreadfully melancholy, he stares inquisitively here and there, and cranes his long neck around the house like a bereaved Vermonter who has just come from the death-bed of his mother-in-law, and is looking for a sexton. For something like a minute, he says not a word, but rubs his hands awkwardly, and continues the search. Finally, just as the spectators are about to break into giggles, he opens his capacious mouth, and begins in a slow drawl,--about three words a minute by the watch.

Mr. Twain took his auditors on a flying trip to California and the mountain mining-regions; giving alternate glimpses of sense and nonsense, of humor, burlesque, sentiment, and satire, that kept the audience in the most sympathetic mood. He dipped into pathos, rose into eloquence, kept sledding right along in a fascinating nasal snarl, looking and speaking like an embarrassed deacon telling his experience, and punctuating his tardy fun with the most complicated awkwardness of gesture. Now he snapped his fingers; now he rubbed his hands softly, like the catcher of the champion nine; now he caressed his left palm with his dexter fingers, like the end minstrel-man propounding a conundrum; now he put his arms akimbo, like a disgusted auctioneer; and now he churned the air in the vicinity of his imperilled head with his outspread hands, as if he was fighting mosquitoes at Rye Beach. Once he got his arms tangled so badly, that three surgeons were seen to edge their way quietly toward the stage, expecting to be summoned; but he unwound himself during the next anecdote.

It is plain to see that Twain's success as a platformer results: first, from his being a genuine humorist with audacity and imagination; secondly, from his slow and solemn speech and his sanctimonious bearing and manner. Then the style of his delivery gives all the effect of spontaneity. The jokes are uttered as if he had just thought of them a minute before, and didn't perceive the point of them quite as soon as his audience.

It would hardly be fair to give a full report of the lecture of Mark Twain last night, as it is to be repeated to-night at the Union-park Church, on the West Side. It is all our fancy painted it, however; and those who do not hear Twain to-night will have cause for perpetual sorrow.