Brooks— T/^e Osteology and Arthrology of the Haddock. 187 



The centrum, in both the neural and haemal canals, is hollowed 

 hj a central depression, the haemal, being the deeper. Followed 

 towards the tail, the vertebrae become gradually smaller, and in 

 the last ten the spines are nearly straight, and are studded with 

 little bony knobs, giving them a knotted appearance. In the 

 antepenultimate vertebra the spines look like hypural bones. The 

 penultimate has no spines, but articulates with two hypural bones 

 below and two similarly-shaped bones above. The last vertebra is 

 ankylosed to a terminal, triangular, bony plate. Followed for- 

 wards beyond the fifth caudal, the haemal canal rapidly widens. 

 On the fourth caudal a ridge appears on the side of the h^mapo- 

 physis. This becomes more pronounced on the third (PL YIII. 

 fig. 22), and presents a secondary ridge in front. The haemal canal 

 is now very wide. In the second the ridges are stronger, and the 

 anterior folded inwards, and their extremity projects like a trans- 

 verse process. The first is a further exaggeration of this condition 

 and the vertebra appears to have a pair of parapophyses nearly 

 identical in shape with those of the last abdominal, and in series 

 with them, but connected near their lower ends, by a ribbon-like 

 piece of bone, with a short haemal spine. All the above-described 

 ridges are in series with the parapophyses. Owing to the increase 

 in size of the haemal canal in the anterior caudal vertebrae, the 

 spines become shorter, though their tips are nearly the same abso- 

 lute distance from the centra. 



The ribs, eighteen in number, are slender, curved bones, all of 

 which articulate with the parapophyses, except the first ; the middle 

 are the longest, about two inches,' and the last is a very slender 

 bone of about half an inch in length; the general inclination is 

 downwards and slightly backwards ; the posterior ribs also incline 

 inwards, being in series with the lower part of the haemal arches 

 of the anterior caudals. The first rib differs both in shape and in 

 manner of articulation from any of the others ; it is stouter pro- 

 portionally, and is from one-half to three-quarters of an inch in 

 length ;' the head is sunk in the above-described pit, in the body 

 of the third vertebra ; at a point about the middle of its dorsal 

 surface it supports the first epipleural spine, which is about twice 

 the length of the rib. The second rib is about the length of the 



^ In a haddock of thirty inches. 



SCIEN. PROC. K.D.S. — VOL. IV. PT. IV. 



