776 J. F. GUDERNATSCH 



cles, 700/x long by 400At broad. Branched follicles are numerous. 

 The epithelial cells are cuboidal in shape. 



PRIONOTUS CAROLINUS BLOCK 



In a sea-robin SO cm. long the thyreoid gland seemed to show 

 a pathological appearance. The invasion of the surrounding 

 tissues by thyreoid follicles was extraordinary, but may be abnor- 

 mal. For this reason it can only be stated that the gland in this 

 species occupies a posterior position, close to the origin of the 

 truncus arteriosus. 



OPSANUS TAU L. 



A toadfish 30 cm. long the gill region in this species is extremely 

 shortened, and therefore the thyreoid region begins rather far 

 forwards. Anteriorly the largest follicles lie on both sides of a 

 process of the copula which extends ventrally (fig. 19, A). Towards 

 the aortic bifurcation the size of the follicles decreases and the 

 two lateral portions unite in the median line, at the same time the 

 lateral extension (fig. 19, B) of the follicles increases remarkably 

 (pi. II, fig. 18). Some follicles appear below the aortic stem. 

 Between the first and second branchial arches the number of 

 follicles decreases above the aorta, while ventrally they disappear 

 entirely. Along the second branchial arteries the follicles again 

 reach laterally and also again appear ventrally. Behind this 

 point the aorta sinks more and more and the space around it 

 becomes freer. Yet there is no special increase of thyroid tissue 

 in this region, there being only loosely scattered small follicles. 

 A few follicles accompany the aorta in its course into the space 

 between the musculus sternohyoideus. The caudal end of the 

 thyreoid lies behind the third gill branches. 



The arrangement of the follicles is loose, and they are usually 

 circular in cross sections. Some are flattened between the bony and 

 muscular surrounding tissues. Their size varies extremely. The 

 largest ones, 600^1 in diameter, lie in the anterior end, which 

 is the reverse of the general rule for other species. In other regions 



