SKELETAL MUSCULATURE OP THE KING SALMON. 



43 



Lying on the dorsal surface of the three centra of the caudal group, and extending 

 out over the bases of the neural spines is an irregularly fan-shaped bony plate, the Deck- 

 knochen der Chorda of von Kolliker." This plate is coalesced into the dorsal surface 

 of the second, and usually the third, centrum. It has a caudally projecting spine extend- 

 ing in the direction of the axis of the third centrum. 



The hemal spines of the last three vertebras of the peduncle are also sharply modified 



Fig. 4. — Caudal skeleton. Five centra of the caudal peduncle with their modified spines are shown. The three caudal centra 

 are much reduced, the last quite rudimentary. The hemal spine of the basal caudal vertebra is very stout. It bears a 

 transverse spine near its base. The lower one of the five bypurals is marked "ft." The large irregular plate **d" is von 

 Kolliker's " Deckkuochen Aez Chorda." ol Salmo salar. A few of the deeper fibers of the muscuU interfilamenti (inJ. )are 

 shown. 



by being greatly thickened and broader. The borders of these plate-like hemal arches 

 are not fused, though they are intimately bound together by connective tissue. 



The hemal spine of the most anterior vertebra of the three that belong to the 

 caudal fin proper is very strong and bar-like. It is heavier than the caudal peduncle 

 spines anterior to it, and is especially characterized by its strong and stocky base which 

 carries a well-developed lateral process. This process stands out sharply for 3 to 5 mm. 



<i Kolliker. Albert von, op. cit.. p. 12. 



