Prof. Owen’s Description of the Lepidosiren annectens. 
Tas. XXVI. 
Circulating and Respiratory Organs of the Lepidosiren annectens, on the scale 
of one inch to half an inch. 
Fig. 1. Branchial and pulmonary apparatus seen from the dorsal aspect. 
a. First lobe of the tongue. 6. Second lobe of the tongue. c. c. Di- 
varicated sides of the pharyngeal aperture, which has been slit 
open. d. Pharyngeal valve. e. Laryngeal aperture. f. Laryn- 
geal or thyroid cartilage. "The figures 1, 2, 3, 4 & 5, indicate the 
interspaces between the six branchial arches on each side, which 
conduct the water to the branchial chamber. k. The membra- 
nous trachea or ductus pneumaticus: its communication with the 
right lung is shown. 
2. The same parts, with the heart, seen from the ventral aspect. a. The 
auricle ; the letter is placed on the left appendix. b. The ventricle, 
laid open to show the termination of the vena pulmonalis, in which 
a black bristle is placed; the wide orifice of the auricle, and the 
aortic opening through which a white bristle is passed. c. The 
bulbus arteriosus, laid open to show the longitudinal valvular pro- 
cesses in its interior. d. Pericardium. e. Vena cava abdominalis. 
J. Vena pulmonalis. g. Arterial trunk common to the systemic, 
branchial and pulmonary circulations. The figures 1,2,3, 4, 5 & 6, 
indicate the branchial arteries on each side, of which the 2nd and 
3rd chiefly go to form the pulmonary artery, I. m. m. The two 
divisions of the pulmonary artery, for the two lungs. n.n. The 
two corresponding veins, which return the aërated blood to H^ 
Tas. XXVII. 
Fig. 1. A scale of the Lepidosiren annectens, magnified eight diameters. 
2. Mouth of the Lepidosiren annectens, 
a. The inserted margin; 5. the thick cuticle reflec 
à i ted from the poste- 
rior margin. 
twice natural size. 
a. The intermaxillary teeth. 6. The three projecting angular pro- 
