SKELETON OF HADDOCK 



619 



are the downward curving ribs, and also more delicate 

 intermuscular bones which curve upwards. In the caudal 

 vertebrae (Fig. 354), the centra (c.) bear not only superior 

 neural processes (n.a.), but also inferior haemal processes 

 (h.a.) ; they are of course without ribs. 



At the end of the vertebral column lies a fan-shaped 

 hypural bone which helps to support the tail, and is 

 developed from an enlarged haemal arch. The fin-rays are 

 jointed flexible rods, which in the dorsal and anal fins 

 are attached to the ends of interspinous 

 bones alternating with the neural and 

 haemal spines, and connected with them 

 by fibrous tissue. 



The skull includes the following bones, 

 which may be grouped in the following 

 regions (the membrane bones in italics) : — 



{a) Around the foramen magnum : basi-occipital. 



two ex-occipitals, and a sw^ra-occipital. 

 {b) Along the roof : si*/)rfl-occipital, paHetals, 



frontals, mesethmoid, nasals. Beneath the 



parietals He the alisphenoids. 

 (c) Along the floor : basi-occipital, parasphenoid, 



vomers, 

 {d) Around the ear on each side : sphenotic, 



pterotic, and epiotic (above), prootic and 



opisthotic (beneath). ^^^ 354.— Cau- 



[e) In front of and around the orbit : parethmoid, dal vertebra of 



lachrymal, orbitals. haddock 



Thus the haddock's skull shows in two «•«•. Neural arch; 



respects an advance upon that of the skate : I'm., hSmai Irch^. ' 

 first, in the ossification of the primitive 

 cartilage ; and second, in the addition of membrane bones. 

 Of the latter, the parietals and frontals cover over the 

 spaces which in the skate form the fontanelles. 



The first or mandibular arch is believed by many to form Meckel's 

 cartilage beneath, and the palato-pterygo-quadrate cartilage above. 

 Meckel's cartilage becomes the foundation of the lower jaw, and bears 

 a large tooth-bearing membrane bone — the dentary, a small corner 

 bone — the angular, while the articular element is a cartilage bone. 

 Of the bones associated with the upper part, the palatine lies in front, 

 the quadrate articulates with the lower jaw ; while between palatine 

 and quadrate lie the pterygoid, the mesopterygoid, and the meta- 

 pterygoid, 



