SEA-FISHERIES LABORATORY. 195 



It articulates as shown in fig. 14 with U + Up. 3 above 

 and in front, the latter articulation making the two ex- 

 panded tail bones unequal. The first ostensible hypural 

 (Hp. 1) is a wedge-shaped bone of the same structure as 

 the 2nd, but much smaller. It is closely attached by liga- 

 ment to the last haemal spine, but proximally does not 

 reach the vertebral column. 



Each bone in the tail giving articulation to fin rays 

 bears a thin terminal cartilaginous epiphysis (cp. fig. 14). 

 As in the other fins there is a pad of sub-cartilaginous 

 tissue intercalated between the bones of the vertebral 

 column and the proximal ends of the fin rays. This, as 

 before, is embraced by the diverging halves of the rays 

 (F.R.). The number of the latter in the caudal fin varied 

 in the specimens examined around 20 — sometimes more 

 and sometimes less. What possibly may be regarded as 

 the typical condition both as regards number and places 

 of articulation is represented as follows (cp. fig. 14) : — 

 Shaft of last neural spine, 1 ; Epural 1, 1 ; Epural 2, 2 ; 

 Hypural 3, 6 ; Hypural 2, 6 ; Hypural 1, 3 ; shaft of last 

 haemal spine, 1 ; total, 20. 



Each fin ray is of the same structure as those of the 

 pectoral and pelvic fins, with the exception that there are 

 no articular processes connecting the individual rays with 

 their neighbours, each ray in the caudal fin, therefore, 

 being independent of those immediately above and below 

 it. With the exception of about the three most dorsal 

 and ventral, each ray bifurcates distally, but does not split 

 up further to form a brush as happens in the caudal fin 

 rays of the Sole according to Cunningham. 



9.—Dorsal Fin (Figs. 17 and 19). 



The dorsal fin commences very far forwards in the 

 pseudo-medial line, and in the specimen on which the 



