30 Descriptions of Preparatioyis. 



intestine to the stomach and commencement of the small intestine 

 as is usually found in vertebrate animals. The position of the 

 tongue in a sheath beneath the trachea which thus interposes itself 

 between that tactile organ and the oesophagus, and also the re- 

 moval of the gall-bladder from immediate connection with the liver 

 down to a level where it is less liable to be injured by sudden 

 pressure, are probably to be regarded as modifications specially 

 subserving the special habits of Ophidia. 



In this specimen, which is thirty inches long, the liver measures 

 about seven and the lung about twelve inches in length. But 

 the walls of the lung are but very lowly vascular after the first 

 three inches of its length. Its blind posterior non-vascular end is 

 seen just anteriorly to the right ovary ; the anterior end of the 

 lung, represented by the development of a spongy layer on one side 

 of the trachea, is seen a little anteriorly to the base of the heart. 

 Just where the trachea begins to lose its distinctive character on 

 the surface of the lung, it gives off the rudimentary left lung, which 

 occupies the angle intercepted between the apex of the heart and the 

 vena cava inferior, as it passes up from the apex of the liver to enter 

 the heart. Midway between the apex of the heart and the apex of 

 the liver a black bristle has been passed between the dorsal aorta 

 which has been raised a little from its natural position some dis- 

 tance below the vertebral column, and the oesophagus, with which 

 it is in close relation below this point. The dorsal aorta is seen to be 

 constituted by the confluence of two trunks, a larger one which 

 gives off no branches, and which as it passes to the left on leaving 

 the heart is called the ' left aorta,' and a smaller one which owes its 

 diminished calibre to the fact of its having given off the arteries of 

 the anterior parts of the body, and which, from the course it takes, 

 is known as the ' right aorta.' The walls of the oesophagus are seen 

 to be thin and lowly, or not at all, muscular. The absence of con- 

 tractile power in this tube is compensated for by the working of 

 certain muscles homologous with the transversales abdominis of an- 

 thropotomy. A slip of blue paper has been passed under a fascicle 

 of one of these muscles immediately opposite the apex of the 

 liver on the left side, whilst on the right the muscle of that side 

 is seen to take origin from the internal aspect of the thoracico- 

 abdominal cavity along a line passing about midway between the 

 ventral apex and the vertebral abutment of each rib. Each muscle 



