602 Mu. n. II. \viiri\"nousE ox the [Apr. ^, 



only is in reality ]iyi)in;il ])\us the last vertebral segment. The distal 

 arms ot" the U -shaped hypuial of the penultimate vertebra often 

 tt'iul to fuse anil so produce an el]i[)tifal l)onc'. There is consider- 

 able variation in the number of fin-rays supported by the various 

 terminal elements ; the terminal dorsal and ventral radial may 

 or may not support a ray. It is usual for the last two hypui-als 

 to sup])ort four rays each, but this too is liable to vjiriation. In 

 youn^ animals it is (piite accidental whether tin-rays bifurcate or 

 not distally, and it is not s,afe to conclude, with Kyder, that 

 bifurcated dermotrichia are caudal proper and others dorsjil or 

 ventral i-espectively. 



Conger VULGARIS. (i\[uraniida\) (Plate XLVllI. fig. 12.) 



In most respects the caudal fin of the Conger is similar to that 

 of AiHjniUa. Oidy by the aid of clearing agents can the exact 

 outline of the various elements be traced ; when thus treated, it 

 is seen that the vertebral column proper ends in a long coi\e-like 

 vertebra, directed posteriorly in a straight line with the vertebral 

 axis, i.e. there is no tendency to upturning, and a ui'ostyle cannot 

 be said to exist. IJut all this is invisible without the aid of 

 clearing agents, and the last centrum aj)pears to be merely the 

 proximal end of the three hypurals, which in reality are tirndy 

 fused with the last centrum. However, any diiliculty concerning 

 the ending of the vertebral axis is removed by a reference to the 

 young stages : a young conger of 3|^ inches (D'O cm.) length or 

 less will show a condition, of things very like those in Avyuilla, 

 viz., a urostylar process npwai-dly directed, and occupying a 

 position along the proximal dorsal edge of the last hypural ; in a 

 specimen 4.4 inches (or 11 "5 cm.) long, this could not be seen in 

 the mere dissection. 



Those dermotrichia which may safely be called caudal are 

 supi)()rtcd l)y four hypural bones : the fii'st of these is attached to 

 the }>enultimate vertebra, instead of the antepenultimate, as in 

 AiKjiiilla, and the remaining three are all fused to the last 

 vertebral segment. In this i-esjx^ct, the Conger diflers from the 

 Common Eel in which only one belongs to the last centrum, and 

 the next two (forming the letter U) to the penultimate vertebra : 

 tliis may i-epresent a further shortening of the vertebral axis in 

 Conger. A word should be said here, calling attention to the 

 excellent illustration afibrded by these hypurals, jjarticularly the 

 fi 1st and second, of their double nature: a line of fusion can be 

 traced across the hy[)Uial dividiug the latter into two parts, the 

 proximal of which is almost exactly similar to the pn ceding ha iiial 

 arches, and the distal part is like a radial. 



There iire no epural bones. The neuial arches closely resemble 

 those of A iKjiilUd, but are more sinijde, the anterioi- oiics pos.sessing 

 a very feeble spine; the la.st, which is specially long, to protect 

 the end of the spinal cord, possesses a jieculiar bony process 

 running in an anterio-ventral direction across the last centrum ; 

 this i.-< jirobably a pi'ocoss for the attachment of caudal muscles. 



