lo C. W. M. Poynter 



trunk may be lacking and be supplied by tbe posterior auricular 

 20 per cent., terminal brandies may be double, 8 per cent. 



A. Car Otis Interna 



The internal carotid is occasionally somewhat irregular in its 

 course, Hyrtl (1841), Tigri (1866), Thompson (1898), Moor- 

 head (1902), Hansen (1903), Sack (1907) ; or tortuous, Stimson 

 (1885). Hulke (1893), Skillern (1912) ; or the caliber varies on 

 the two sides, Hyrtl (1836), Orr (1906). One vessel may be 

 lacking, Tode (1787), Quain (1844), Wyeth (1878), Flemming 

 (1894), Fisher (1913), Timbrell (1913), Lowrey (1916). 



The third portion of the artery is more subject to variations than 

 the other portions. In the cavernous sinus a branch may arise and 

 pass backward to join the basilar, Quain, Tiingel (i860), Duret 

 (1873), Tigri (1866), Miiller (1871), Tareniecki (i88oj, Hoch- 

 stetter (1885), Windle (1887), Smith (1909). The latter thinks 

 that the condition is due to the persistence of an aberrant vessel 

 developing early when the two are in close proximity. 



A. OphtJialniica 



The ophthalmic artery is the first branch to develop from the 

 internal carotid and appears about the 7-mm. stage. The hyaloid 

 develops from this at a somewhat later period, Dedekind (1909). 

 The ophthalmic may be unassociated with the internal carotid, but 

 may come from the middle meningeal, 1. c, or it may consist of a 

 trunk to the retina only and the other orbital vessels be derived 

 from neighboring arteries, Carnow (1874), or it may be double, 

 Barkow (1866). 



The lachrymal may be wanting or supplied by some other vessel, 

 most frequently the supra-orbital is the continuation of the lachry- 

 mal. Cruveilhier considers that the nasalis is normally a branch 

 of the angular ; Dall'Acqua (1906) finds this true in only 5 per cent. 



The hyaloid artery appears in the 22-mm. stage as a branch from 

 the nasal side of the common ciliary; Versari (1903) and Fuchs 

 (1890) say it atrophies soon after birth. Miiller (1856) reported 

 finding the artery frequently in the ox and predicted that such a 

 condition would be discovered in the human eye. The prediction 



