It is probable, however, that these resemblances are mainly due to parallelism in development, and are in all three cases adaptations necessary to support the enormous weight of the body. On the other hand, the marked resemblance of the structure of the tarsus is probably indicative of descent from nearly allied condylarthrous ancestors (see PHENACODUS). No importance can be attached to the presence of horns as an indication of affinity between _Arsinoitherium_ and the Amblypoda; and there are important differences in the structure of the skulls of the two, notably in the external auditory meatus, the occiput, the premaxillae, the palatal foramina and the lower jaw. From the Proboscidea _Arsinoitherium_ differs broadly in skull structure, in the form of the cheek-teeth, and in the persistence of the complete dental series of forty-four without gaps or enlargement of particular teeth. Whether there is any relationship with the Hyracoidea cannot be determined until we are acquainted with the forerunners of _Arsinoitherium_, which is evidently a highly specialized type. It may be added that as the name Barypoda has been used at an earlier date for another group of animals, the alternative title Embrithopoda has been suggested in case the former should be considered barred. See C.W. Andrews, _Descriptive Catalogue of the Tertiary Vertebrata of the Fayum, British Museum_ (1906). (R. L.*) ARSON (from Lat. _ardere_, to burn), a crime which has been described as the malicious and voluntary burning of the house of another (3 Co. _Inst._ 66). At common law in England it is an offence of the degree of felony. In the Roman civil law arson was punishable by death. It appears early in the history of English law, being known in ancient laws by the term of _boernet_. It is mentioned by Cnut as one of the bootless crimes, and under the Saxon laws was punishable by death. The sentence of death for arson was, says Stephen (_Commentaries_, iv. 89), in the reign of Edward I. executed by a kind of _lex talionis_, for the incendiaries were burnt to death; a punishment which was inflicted also under the Gothic institutions. Death continued to be the penalty at least down to the reign of King John, according to a reported case (Gloucester Pleas, pl. 216), but in course of time the penalty became that of other common-law felonies, death by the gallows. It is one of the earliest crimes in which the _mens rea_, or criminal intent, was taken special notice of. Bracton deals at length with the _mala conscientia_, which he says is necessary for this crime, and contrasts it with _negligentia_ (f. 146 b), while in many early indictments malice aforethought (_malitia praecogitata_) appears. Arson was deprived of "benefit of clergy" under the Tudors, while an act of 8 Henry VI. c. 6 (1429) made the wilful burning of houses, under particular circumstances, high treason, but acts of 1 Ed. VI. c. 12 (1547) and 1 Mary (1553) reduced it to an ordinary felony.