NOTES ON A SCINK WITH AN ACCESSORY TAIL. Ill 



btill ill the main tai] a typical medullated caudal vertebra with a complete 

 neural arch that encloses the spinal cord of perfectly normal appearance. 

 The same might be said of the region marked ((3) in fig. 2, whence the 

 section of fig. G is taken. Here the accessory tail is already entirely 

 separated from the main-tail, and the section passes through the spinous 

 process as well as the posterior articular processes of the vertebra seen in 

 fig. 5 and also through the intervertebral cartilage directly following that 

 vertebra. The gap of the vertebral column on either side of the spinal 

 cord is the foramen through which the roots of the spinal nerve find 

 their exit. The section had passed rather obliquely so that while it 

 strikes on the one side a spinal ganglion, it does not do so on the other, 

 where, on the other hand, a portion of the anterior articular process ol 

 the next following vertebra has been included. It may here be men- 

 tioned that the pair of spinal nerves seen on this plane is the last left in 

 the main tail. 



In a few successive sections which immediately follow the one 

 represented in fig. 6, a normal vertebra with medullated body and 

 neural arch is again revealed, soon however to give place to the 

 characteristic cartilaginous cylinder of the regenerated tail (figs. 7, 8 

 and 9). The cylinder gradually becomes thinner as we trace it pos- 

 teriorly, without showing any constriction at whatever intervals. As to 

 its structure I have nothing to add to what is already known through 

 the works of Gegenbaur, ^ Fraisse - and others ; but one point that I 

 wish to state with special emphasis is the fact that its lumen contains, 

 in my s]wcimen, a tolerably well regenerated continuation of the spinal 

 cord although it nowhere gives off any nerve. Fig. 9 is a highly 

 magnified vievv' of the cartilaginous cylinder and its contents from the 

 same section as fig. 8 which crosses the main tail at so posterior a 

 position as is marked (8) on fig. 1. There is between the cartilaginous 

 wall and the spinal cord, a layer of connective tissue (containing fatty 



1 Gegenbaur, c, TJnters. z. vergl. Anat. d. Wirblsiiure b. Amp. xi. Rep. Leipzig. 1862. 



2 Fraisse, T., Ueber d. Regeneration vou Oi-ganen und CTeweben bei Auip. n. Rep. 

 Tagebl. d. 52. Versaumil. deutsch. Xaturf. 



