OF THE VALVES OF THE VASCULAR SYSTEM IN VERTEBRATA. 805 



Fig. 39. Bulbus Arteriosus and Ventricle of Sturgeon, — the former displaying five rows of semi- 

 lunar valves (a), the latter an auriculo-ventricular valve (6), with numerous tendinous 

 bands running into it. (See p. 779,) 



Fig. 40. Bulbus Arteriosus and Portion of Ventricle of Lepidosteus. Shows the great thickness of 

 the bulb (a), and of the valves (6) contained within it, and between which tendinous 

 bands run. (See p. 780.) 



Fig. 41. Portion of Bulbus Arteriosus of Basking Shark. Shows the great thickness of the bulb 

 (a) and of the valves (6), and how the latter support each other. (See p. 780.) 



Fig. 42. Heart of Crocodile. Shows spiral semi-muscular, semi-tendinous valve (r), situated between 

 right auricle (a) and ventricle (x). (See p. 781.) 



Fig. 43. Bulbus Arteriosus and Ventricle of Sun-fish. Shows three semilunar valves (a b c) at orifice 

 of bulb, and an auriculo-ventricular valve (/), consisting of two segments. (See pp. 779, 

 781.) 



Fig. 44. Heart of Serpent {Python tigris). Shows muscular semilunar valve at orifice of left superior 

 cava {s) ; also spiral muscular slit (r), occurring between the ventricles. (See pp. 781, 782). 



Fig. 45. Heart of Emu, showing spiral muscular valve {g h), occurring in right auriculo-ventricular 

 orifice. (See p. 781.) 



Fig. 46. Heart of Swan, with right and left ventricles laid open. Shows spiral muscular valve of 

 right ventricle (?'), and miti'al valve (y) of left, and how one portion of the former (J) 

 corresponds in position to the anterior musculus papillaris (y) of the latter. (See p. 781.) 



Fig. 47. Heart of Frog-fish. Shows three sets of semilunar valves ; one occurring where the large 

 veins join the auricle (c) ; a second, where the auricle opens into the ventricle (6) ; the 

 third being situated at the orifice of the bulbus arteriosus (a). (See p. 779.) 



Fig. 48. Bulbus arteriosus and portion of Ventricle of Grey Shark. Shows semilunar valves, with 

 tendinous chords running between them (a) ; also, auriculo-ventricular valve (g). (See pp. 

 779, 780.) 



Fig. 49. Wax cast of Left Ventricle (6) and portion of Right Ventricle (a) of Deer. Shows spiral 

 nature of the left ventricular cavity, — the spiral course or tracks of the musculi papillares 

 (xy), and how between these, two spiral grooves {j q) occur, which direct the blood on to 

 the segments of the mitral valve in spiral waves. (See pp. 784, 785.) 



Fig. 50. Plaster of Paris cast of Right and Left Ventricles of Zebra. Shows infundibulum or conus 

 arteriosus (i) of right ventricle, and analogous portion of left ventricle (^p 0) ; also three 

 prominences on each (d e kr v), corresponding to the sinuses of Valsalva. It also shows 

 the double cone formed by the left ventricular cavity, the one apex pointing towards the 

 apex of the heart [j), the other towards the aorta (Ji). (See pp. 784, 785.) 



Fig. 51. Same cast seen posteriorly. Shows the mitral (mn) and tricuspid (g h) valves in action, 

 and how the blood, when these are closed, assumes a conical form (0) for pushing aside 

 the segments of the semilunar valves, and causing them to fall back upon the sinuses of 

 Valsalva (y lu). It also shows how the right ventricular cavity (c) curves round the 

 left one (x), and how the pulmonary artery (6) and aorta (h) pursue different directions. 

 (See pp. 784, 785.) 



Figs. 52, 53, and 54. Show the Mitral (r s) and Tricuspid (m i n) Valves of the Sheep in action. How 

 the segments, acted upon by the spiral columns of blood, roll up from beneath towards the 

 end of the diastole (fig. 52) ; how, at the beginning of the systole, they are wedged and 

 twisted into each other, on a level with the auriculo-ventricular orifices (fig. 53) ; and 

 how, if the pressure exerted be great, they project into the auricular cavities (fig. 54). 

 (See pp. 796, 797, 798, 799, 800, 801.) 



Figs. 55, 56, and 57. Show the same in the Human Heart, with this difference, that in the right 

 ventricle, a true mitral valve (m n), as not unfrequently happens, has taken the place of 

 the tricuspid. (See pp. 796, 797, 798, 799, 800, 801.) 



Note. — The spiral downward movement of the mitral and tricuspid valves has only been partially 

 represented (figs. 52 and 55) owing to the great difficulty experienced in representing spiral 

 cavities, 



VOL. XXIir. PART III. 10 F 



