254 s. "WATASE 



most hœmal process ( 6.) there is a series of four bones (a, h, c, d), 

 Avhose anterior extremities are wedged into the space between the two 

 pieces of the nrostyle. A narrow space on the line of prolongation 

 of the vertebral axis divides the whole series of hypural bones — as 

 the bones under the urostyle have been called — into two groups. 

 The posterior edges of these hypural bones are all truncated in much 

 the same way, and present an almost even line at which the caudal fin- 

 rays are attached. The seven flat hypural bones and the two haemal 

 spines from the penultimate and ante-penultimate centra support the 

 rays of the ventral lobe of the caudal fin. 



Between the urostyle and the neural spine from the penulti- 

 mate centrum there is found a freely suspended piece of bone — the 

 ^^ falscher Dorn'' (f.d.). The urostyle, the "falscher Dorn'' and 

 the two neural spines from the penultimate and the ante-penultimate 

 centra, constitute bony supports for the rays of the dorsal lobe of 

 the caudal fin. 



It is thus apparent that the greater portion of the tail is to be 

 designated as the ventral lobe while the dorsal portion occupies only 

 a comparatively insignificant part of the whole. The original diphy- 

 cercal state, in which the ventral and dorsal lobes were equally distri- 

 buted on both sides of the vertebral axis, is now disturbed by the 

 upturning of the latter near its caudal termination. The great 

 development of the inferior appendages and the backward condition of 

 the superior consequent on this, resulted in the expanded, fan-shaped 

 arrangement of the caudal skeleton. 



AVith this brief description of the bony elements in the vertical 

 form of the tail, we proceed to the examination of those of gold-fishes 

 in various stages of modification. We will first take up a gold-fish 

 with the tail divided in three distinct lobes as shown in Fig. 7. In 

 comparing tlie caudal skeleton of such a form with that of a vertical 



