(The garment...too quadrangular, p.5.)
Speaking of the Greek priests of Korfou, the erudite Bishop of Lincoln, lately deceased, has remarked, "There is something very picturesque in the appearance of these persons, with their black caps resembling the modius seen on the heads of the ancient statues of Serapis and Osiris, their long beards and pale complexions, and their black flowing cloak, -- a relic, no doubt, of the old ecclesiastical garment of which Tertullian wrote." These remarks  are illustrated by an engraving on the same page.
He thus identifies the pallium with the gown of Justin Martyr;  nor can there be any reasonable doubt that the pallium of the West was the counterpart of the Greek phelonion and of the phailone, which St. Paul left at Troas. Endearing associations have clung to it from the mention of this apostolic cloak in Holy Scripture. It doubtless influenced Justin in giving his philosopher's gown a new significance, and the modern Greeks insist that such was the apparel of the apostles. The seamless robe of Christ Himself belongs to Him only.
Tertullian rarely acknowledges his obligations to other Doctors; but Justin's example and St. Paul's cloak must have been in his thoughts when he rejected the toga, and claimed the pallium, as a Christian's attire. Our Edinburgh translator has assumed that it was the "ascetics' mantle," and perhaps it was.  Our author wished to make all Christians ascetics, like himself, and hence his enthusiasm for a distinctive costume. Anyhow, "the Doctor's gown" of the English universities, which is also used among the Gallicans and in Savoy, is one of the most ancient as well as dignified vestments in ecclesiastical use; and for the prophetic or preaching function of the clergy it is singularly appropriate. 
"The pallium," says a learned author,  the late Wharton B. Marriott of Oxford, "is the Greek himation, the outer garment or wrapper worn occasionally by persons of all conditions of life. It corresponded in general use to the Roman toga, but in the earlier Roman language, that of republican times, was as distinctively suggestive of a Greek costume as the toga of that of Rome." To Tertullian, therefore, his preference for the pallium was doubtless commended by all these considerations; and the distinctively Greek character of Christian theology was indicated also by his choice. He loved the learning of Alexandria, and reflected the spirit of the East.
(Superstition, p.10, near note 9.)
The pall afterwards imposed upon Anglican and other primates by the Court of Rome was at first a mere complimentary present from the patriarchal see of the West. It became a badge of dependence and of bondage (obsta principiis). Only the ornamental bordering was sent, "made of lamb's-wool and superstition," says old Fuller, for whose amusing remarks see his Church Hist., vol. i. p.179, ed.1845. Rome gives primitive names to middle-age corruptions: needless to say the "pall" of her court is nothing like the pallium of our author.
 Wordsworth's Greece, p. 263. London, 1839.  See vol. i. p. 160, this series.  But it was assuming a questionable point (See Kaye, p. 49) to give it this name in the title, and I have retained it untranslated.  See note on p. 160 of vol. i., this series.  See his valuable and exhaustive treatise, the Vestiarium Christianum, especially pp. 73, 125, 233, 490. Also, for the Gallicanum, p. 204 and Appendix E., with pp. 210, 424. For the Græcum, pp. xii. (note), xv. 73, 127, 233.
 See vol. i. p. 160, this series.
 But it was assuming a questionable point (See Kaye, p. 49) to give it this name in the title, and I have retained it untranslated.
 See note on p. 160 of vol. i., this series.
 See his valuable and exhaustive treatise, the Vestiarium Christianum, especially pp. 73, 125, 233, 490. Also, for the Gallicanum, p. 204 and Appendix E., with pp. 210, 424. For the Græcum, pp. xii. (note), xv. 73, 127, 233.