49 



auricle, pulmonary artery, and aorta, to show the valves in their 

 interior. The front ventricular wall can be removed to show the 

 cavities of the ventricles and the auriculo-ventricular valves, 



219. Model of the human heart, similar to No. 218, 

 and constructed by the same makers. 



Exhibited by G. Gill tf Co. 1878. Price 22s. 6d. 



220. Model of the human heart, much enlarged, 

 mounted 011 a board. 



Exhibited by R. M. Cameron fy Son. 1879. 



Price 21. 2s. 



The anterior wall lifts off to show the interior of the four 

 cavities with their valves and the root of the pulmonary artery 

 with its valves. 



221. Model of the human heart, enlarged. 



From the Pedagogical Museum, St. Petersburg. 

 E. 668. 1877. 



Portions of the walls are movable, to show the various cavities 

 with their valves. 



222. Enlarged model of the human tongue, hyoid 

 bone, and larynx. 



E. 20. 1862. Made by the late Dr. Auzoux, Paris. 



The first two can be separated from the last. The integu- 

 ment of the dorsum and of the right side of the toDgue can be 

 lifted off, as well as the glosso-pharyngeal muscle from the left 

 side ; here also the hyo-glossus muscles are separable The left 

 half of the body of the tongue can be taken off to exhibit the 

 fan-like arrangement of the fibres of the genio- hyo-glossus muscle. 

 The hyoid bone is thus left exposed on one side with its greater 

 and lesser cornua. On the right side the submaxillary salivary 

 gland and the submaxillary ganglion, as well as the sublingual 

 salivary gland, are left. 



A hook attached to the thyro-hyoid ligament in front allows 

 the larynx to be removed from the tongue and hyoid, and the 

 thyro-hyoid muscles on either side are alsa movable. The crico- 

 thyroid muscles lift out on each side, and then by undoing a 

 hook attached to the crico-thyroid ligament anteriorly and 

 turning back the hinged right half of the thyroid cartilage, the 

 whole of this latter can be removed. A small portion of the 

 middle of it, however, is represented as being lefi attached to 

 the crico-thyroid ligament in front so as to maintain the con- 

 nexions of the muscles and vocal cords. A hook on the back 

 liberates the trachea from the cricoid cartilage. The lateral 

 and posterior crico arytenoid muscles are movable, and then a 



