306 EDUARD UHLENHUTH. 



(A. tigrinuni) the lateral portions may develop into normal 

 thyroids of considerable size. 



The thyroid rudiments of Typhlomolge occupy a position 

 closely resembling the location of the various thyroid portions of 

 the Ambvstomidae. 



Typhlomolge I, a sex-mature animal of in mm. total length 

 and 58.2 mm. body length, does not possess even vestiges of a 

 thyroid. The region of the lower jaw, throat, and heart was 

 sectioned into a complete series; no section is missing. The 

 anterior cardinal vein was followed in its entire course, the 

 visceral cartilages and muscles were carefully searched through, 

 but no traces of a thyroid could be found. 



Typhlomolge 3, a small, apparently young, animal of 57.7 mm. 

 total length and 32.6 mm. body length possesses a median thyroid 

 rudiment. It is entirely detached from the pharyngeal epithe- 

 lium and partly imbedded into the muscles just ventral to the 

 basibranchial (genio-hyoideus). It is located between the at- 

 tachments, to the basibranchial, of the hyoids and first gill arches 

 and just anterior to the latter ones. The tissues are not well 

 preserved, but the rudiment is seen to consist of several vesicles 

 possessing epithelial walls and containing no colloid. No other 

 epithelial structures were found, although the anterior cardinal 

 vein was searched in its entire course dow r n to the Ductus cuvieri, 

 and the lymphatic space, the muscles, and cartilages of the vis- 

 ceral skeleton were carefully inspected. 



In Typhlomolge 7, an animal of 75. 6 mm. total length and 43.1 

 mm. body length, a median rudiment is attached to the ventral 

 surface of the muscles just ventral to the basibranchial, about in 

 the middle between the attachments of the hyoid and first gill 

 arches (Fig. 2). It consists of a single solid cell mass of epithelial 

 structure (Fig. 3). In the center a network-like structure is no- 

 ticed, produced very likely by the cell walls of the clear inner 

 cell ends; the same structure is frequently found in tangential 

 sections through the walls of the follicles of normal thyroids. 

 No colloid is contained in this rudiment. In addition to the 

 median rudiment, two lateral rudiments are present, one on each 

 side. The anterior ends of these rudiments are located near the 

 connection between ceratobranchial and epibranchial of the first 



