With us, the antiphon generally is a verse or verses from Scripture, recited before and after each psalm. "The verse which serves as the antiphon text contains the fundamental thought of the psalm to which it is sung and indicates the point of view from which it is to be understood. In other words, it gives the key to the liturgical and mystical meaning of the psalm, with regard to the feast on which it occurs" (Cath. Encycl., art. "Antiphon").
Psalms. In the Breviary, before the recent reform, twelve psalms were recited in the first nocturn of Sundays and on ferias. This recitation of twelve psalms was, Cassian tells us, caused by the apparition of an angel, who appeared to the monks and sang at one session twelve psalms, terminating with Alleluia. The event was mentioned at the Council of Tours, In the new reform, nine psalms are recited at Matins; they should, the old writers on liturgy tell us, remind us of the nine choirs of angels who without ceasing sing God's praise.
In the new Psalter, the Psalms have been divided into two large divisions, Psalms I.—CVIII. being assigned to the night Office, Matins; and Psalms CIX.—CL. for the day Offices, Lauds to Compline. From this latter division has been made:—
(1) a selection of psalms suitable by their character and meaning to Lauds (vide infra, psalms at Lauds);
(2) a selection of psalms suitable to Compline;
(3) the psalms long used in the small Hours of Sunday's Office;
(4) the first psalms assigned by Pope Pius V. to Prime on Monday, Tuesday, Wednesday, Thursday and Friday.
The remaining psalms are divided into seven groups, in simple numerical order. The psalms of Matins generally come first, and are followed immediately by the groups of psalms for the day Hours.
In the new Breviary, seven new canticles are added to the ten, which stood in the older book. The ten taken from the old and from the new Testament are Audite coeli (Deut., chap. 32) in Lauds for Saturday; Benedicite (Daniel, chap. 3) Sunday's Lauds; Cantemus (Exod., chap. 15) Thursday's Lauds; Confitebor (Isaias, chap. 12) Monday's Lauds; Domine audivi (Habacuc, chap. 3) Friday's Lauds; Ego dixi (Isaias, chap. 38) Tuesday's Lauds; Exultavit (I. Kings, chap 2) Wednesday's Lauds. From the new Testament we have Benedictus, Magnificat, Nunc dimittis. To these are now added Audite verbum (Jeremias, chap. 31), Benedictus es (I. Paralip., chap. 29), Benedictus es (Daniel, chap. 3), Hymnum cantemus (Judith, chap. 16), Magnus es (Tobias, chap. 13), Miserere nostri (Ecclus. 36), Vere tu es Deus (Isaias, chap. 45). (Cf. The New Psalter, Burton and Myers, pp. 51-52).
"The psalms retain the accentuation of the Latin words, which was inserted at the request of Pius V. in the Reformed Breviary of 1568; and also the asterisk, which was introduced to mark the division of the verses of the Psalms in Urban VIII.'s Reform in 1632." The verse division of the psalms do not, in the Breviary, always coincide with those of the Vulgate—e.g., Psalm X.:—