740 



J. F. GUDERNATSCH 



Fig. 1. Sections through the thyreoid gland of Anguilla. yl, anterior to the aor- 

 tic bifurcation; B, between the first and second branchial arteries. Thyreoid 

 follicles in all figures shown in solid black. Transverse muscles lined. Long-mas- 

 cles in polygons. Skeletal parts stippled. Arteries heavy line. Veins light line. 

 Lymph sinus broken line. A, ventral aorta. Ai, An, Am, branchial arteries. 



entire space between the first gill arches, about 2.5 mm. The 

 layer of follicles is very thin so that the dorso-ventral extension 

 is slight. Near the union of the two first gill arteries the follicles 

 are somewhat more dispersed, and reach out dorsally along the 

 sides of the basibranchiale. Some follicles actually lie dorsal to 

 the skeletal parts. The thyreoid is in contact with the first gill 

 arteries for a short distance, and here it reaches its maximal 

 extension. Further back it is limited to the neighborhood of the 

 ventral aorta. 



Behind the aortic bifurcation the follicles lie closely above 

 and to the sides of the aortic stem and extend along it to the 

 second gill arteries. A string of folhcles lies separated between 

 the first and second arterial branches. Baber states that in the 

 conger eel the gland is in the first bifurcation and forms a reddish 

 flattened body. This would correspond to the region of maxi- 

 mal dispersion of thj^reoid follicles in the species here mentioned. 



The follicles exhibit a variety of shapes, elliptical ones being 

 in the majority. They are rather small, lOO/i representing the 

 average diameter of the circular follicles. A few very large fol- 

 hcles are present; these 'giant' folhcles as they might be called, 

 are of elliptical shape measuring 600// in the long and 200ju in the 



