ON THE CAUDAL AND ANAL FINS OF GOLD-FISHES. 257 



spines. The above is the usual arrangement that is to be met with 

 in Teleostei. In the gold-fish however, appendages in the caudal 

 extremity may start in pairs and end as such, somewhat like hœmal 

 appendages in the trunk region. 



It now remains to consider the system of caudal fin-rays, which 

 in fact plays a very significant part in causing the anomalous 

 phenomena of the tail of gold-fishes. Each fin-ray consists of a pair 

 of similar parts running along-side and closely applied to each other 

 for the greater part of their length. At the proximal extremity the 

 two diverge a little and firmly clasp the terminal portion of the 

 caudal skeleton. They are smooth and simple at the base, but 

 become distally segmented into a number of small joints and moreovej 

 longitudinally split into a number of finer rays. Crescentic marks 

 surrounding the caudal skeletons in Figs. 19 — 23 show the distribu- 

 tion of fin rays in various forms of the tail. 



It will now be easy to conceive in what light the three or four 

 lobed tails are to be regarded in relation to an erect and normal form. 

 Thus, when a normal tail with an emarginate outline (Fig. 14, PL 

 XIX), is split into two halves in a vertical plane, each half retaining 

 its emarginate form, the "four- lobed tail" comes into existence 

 (Fig. 15). When the splitting is not complete and the two halves 

 remain united at their dorsal edge, the form known as the tri-lobed 

 tail is the result (Fig. 16). 



The Anal Fin. The anal fin of gold-fishes in its vertical form 

 consists of nine fin-rays, supported by seven inter-haemal bones. 

 These numbers how^ever vary to a certain extent with the in- 

 dividual. The first three of the fin-rays are solid spines, of which 

 the third is the longest and the strongest of all. The following six 

 fin rays branch into finer rays. The inter-hœmal bones bring the 

 anal fin into connection with the hœmal spines. 



