774 J. F. GUDEENATSCH 



The epithelium is rather low, even in the smallest follicles. 

 Branched follicles are numerous. The blood supply is rich, many 

 capillaries being present around the follicles. There are several 

 larger veins running through the thyreoid region. 



TAUTOGOLABRUS ADSPERSUS WALBAUM 



Length of specimen 25 cm. In the cunner the thyreoid gland 

 occupies a unique position, almost resembling that in the sharks. 

 It is pushed far forward in the aortic bifurcation, and touches both 

 the first branchial arteries laterally (fig. 17, B), but does not 

 extend far enough back to come into contact with the ventral 

 aorta (pi. II, fig. 16). The main mass is, as it were, imbedded in 

 a bony capsule. The follicles are grouped around a median vein 

 (fig. 17, A). Dorsal to the aortic bifurcation the copula and a 

 transverse muscle are well developed, so that the thyreoid is forced 

 forward. The follicles are not numerous, and are all more or less 

 irregular. Their diameters measure from 15 to 200/x. The 

 follicular epithelium is cuboidal. 



TAUTOGA ONITIS L. 



Specimen 35 cm. long. In the closely related tautog the thyreoid 

 gland also occupies a rather cephalad position (pi. II, fig. 17). 

 It extends back from within the aortic bifurcation almost to the 

 second branchial arteries. It lies chiefly above and to the sides 

 of the aorta. The anterior, main part, is imbedded in an osseous 

 capsule which is square in cross section, and is formed by three 

 branchial bones above and a ventral supporting bone (fig. 18, A). 

 At the aortic bifurcation the capsule becomes incomplete and the 

 follicles are widely dispersed over 6 mm. (fig. 18, B). The folli- 

 cles follow the dorsal side of the first arterial branches out to the 

 base of the gills. Behind the first branchial arteries the lateral 

 extension decreases and the follicular dispersion is in a dorso-ven- 

 tral direction. The follicles are loosely arranged, and yet globu- 

 lar ones are rare, most of them being polygonal in outline. The 

 average size is 150/i in diameter, but there are a few giant foUi- 



