308 



EDUARD UHLENHUTH. 



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if there are any they must be very small. The lateral rudiments 

 consist of a series of tiny epithelial cell masses; some of them are 

 solid, others are hollow, but none of them contain colloid. 



In Typhlomolge 6, the smallest and probably youngest animal 

 (56.0 mm. total length and 32.0 mm. body length), no median 

 but one lateral rudiment on each side is present. They consist of 

 a series of cell masses (Fig. 5), some of which are solid while 



others contain a lumen. Colloid 

 is absent in all of them. The 

 location is similar to that of the 

 lateral rudiments of the previous 

 specimen. In particular they do 

 not touch the lymph space and 

 are situated dorsal to the place 

 where the anterior cardinal vein 

 comes into contact with this 

 space. They are without a blood 

 supply resembling that of a 

 thyroid. 



In Typhlomolge 2, an animal of 

 77.5 mm. total length and 43.6 

 mm. body length, only the lat- 

 eral rudiments are present. 

 Their location is the same as that 

 of the lateral rudiments described 

 above. Instead of being broken 



FIG. 5. Location of lateral thyroid 

 rudiment of Typhlomolge 6. I., first 



gill arch; II., second gill arch; s.basi- up into several separate cell 

 branchial; GI, blade of first gill; G 2 , masses, each of them has the 



blade of second gill; H. hyoid; L, gh Qf Qne continuous gpithel- 



lymph space; M, cavity of mouth; O, 



opercuium; P. pericardium; T. thyroid, ial cell tube possessing a narrow 



lumen (Fig. 6). 



In Typhlomolge 5, an animal of 66.0 mm. total length and 36.5 

 mm. body length, only one lateral rudiment, the left one, is pres- 

 ent. It is located near the connection between the cerato- 

 branchial and epibranchial of the first gill arch, median to it and 

 anterior to the location of a normal thyroid of Ambystoma 

 opacum. It is composed of a small number of vesicles (Fig. 7) 

 which, instead of being arranged in an antero-posterior row as in 

 the other specimens, are crowded together in one place. The 



