Phylogeny.--Brauer, Lubbock, Sharp, Borner, &c. (opp. cit.); P. Mayer (_Jena, Zeits. Naturw._ x., 1876); B. Grassi (_Atti R. Accad. dei Lincei, Roma_ [4], iv., 1888, and _Archiv ital. biol._ xi., 1889); F. Muller, _Facts and Arguments for Darwin_ (trans. W. S. Dallas, London, 1869); N. Zograf (_Congr. Zool. Int._, 1892); E. R. Lankester (_Quart. Journ. Micr. Sci._ xlvii., 1904); G. H. Carpenter (_Proc. R. Irish Acad._ xxiv., 1903; _Quart. Journ. Micr. Sci._ xlix., 1905). (D. S.*; G. H. C.) HEXASTYLE (Gr. [Greek: hex], six, and [Greek: stylos], column), an architectural term given to a temple in the portico of which there are six columns in front. HEXATEUCH, the name given to the first six books of the Old Testament (the Pentateuch and Joshua), to mark the fact that these form one literary whole, describing the early traditional history of the Israelites from the creation of the world to the conquest of Palestine and the origin of their national institutions. These books are the result of an intricate literary process, on which see BIBLE (Old Testament: _Canon_), and the articles on the separate books (GENESIS, EXODUS, LEVITICUS, NUMBERS, DEUTERONOMY and JOSHUA). HEXHAM, a market town in the Hexham parliamentary division of Northumberland, England, 21 m. W. from Newcastle by the Carlisle branch of the North-Eastern railway, served also from Scotland by a branch of the North British railway. Pop. of urban district (1901) 7107. It is pleasantly situated beneath the hills on the S. bank of the Tyne, and its market square and narrow streets bear many marks of antiquity. It is famous for its great abbey church of St Andrew. This building, as renovated in the 12th century, was to consist of nave and transepts, choir and aisles, and massive central tower. The Scots are believed to have destroyed the nave in 1296, but it may be doubted if it was ever completed. In 1536 the last prior was hanged for being concerned in the insurrection called the Pilgrimage of Grace. The church as it stands is a fine monument of Early English work, with Transitional details. Within, although it suffered much loss during a restoration c. 1858, there are several objects of interest. Among these are a Roman slab, carved with figures of a horseman trampling upon an enemy, several fine tombs and stones of the 13th and 14th centuries, the frith or fridstool of stone, believed to be the original bishop's throne, and the fine Perpendicular roodscreen of oak, retaining its loft. The crypt, discovered in 1726, is part of the Saxon church, and a noteworthy example of architecture of the period. Its material is Roman, some of the stones having Roman inscriptions. These were brought from the Roman settlement at Corbridge, 4 m. E. of Hexham on the N. bank of the Tyne; for Hexham itself was not a Roman station. In 1832 a vessel containing about 8000 Saxon coins was discovered in the churchyard. Fragments of