§50. Under the Republic the patricians had almost without exception this third or family name; we are told of but one man, Caius Marcius, who lacked the distinction. With the plebeians the _cognomen_ was not so common, perhaps its possession was the exception. The great families of the Marii, Mummii, and Sertorii had none, although the plebeian branches of the Cornelian gens (§48), the Tullian gens, and others, did. The _cognomen_ came, therefore, to be prized as an indication of ancient lineage, and individuals whose nobility was new were anxious to acquire it to transmit to their children. Hence many assumed _cognomina_ of their own selection. Some of these were conceded by public opinion as their due, as in the case of Cnaeus Pompeius, who took _Magnus_ as his _cognomen_. Others were derided by their contemporaries, as we deride the made-to-order coat of arms of some nineteenth century upstart. It is probable, however, that only nobles ventured to assume _cognomina_ under the Republic, though under the Empire their possession was hardly more than the badge of freedom.
§51. Additional Names.--Besides the three names already described, we find not infrequently, even in Republican times, a fourth or fifth. These were also called _cognomina_ by a loose extension of the word, until in the fourth century of our era the name _agnomina_ was given them by the grammarians. They may be conveniently considered under four heads:
In the first place, the process that divided the gens into branches might be continued even further. That is, as the _gens_ became numerous enough to throw off a _stirps_, so the _stirps_ in process of time might throw off a branch of itself, for which there is no better name than the vague _familia_. This actually happened very frequently: the _gens Cornelia_, for example, threw off the _stirps_ of the _Scipiones_, and these in turn the family or "house" of the _Nasicae_. So we find the quadruple name _Publius Cornelius Scipio Nasica_, in which the last name was probably given very much in the same way as the third had been given before the division took place.
§52. In the second place, when a man passed from one family to another by adoption (§30) he regularly took the three names of his adoptive father and added his own _nomen gentile_ with the suffix _-anus_. Thus, Lucius Aemilius Paulus, the son of Lucius Aemilius Paulus Macedonicus (see §53 for the last name), was adopted by Publius Cornelius Scipio, and took as his new name _Publius Cornelius Scipio Aemilianus_. In the same way, when Caius Octavius Caepias was adopted by Caius Julius Caesar, he became _Gaius Iulius Caesar Octavianus_, and is hence variously styled Octavius and Octavianus in the histories.