SKELETON. 



XV 



concave bones is covered in by connecting' ligaments, and filled with a 

 gelatinous substance, the remains of the notocord : consequently, clastic 

 balls of semi-fluid consistence exist between each vertebra, enabling them 

 to move very freely one upon another. 



' The abdominal vertebra?, or those belonging to the trunk, have two 

 superior or dorsal processes, which pass upwards and coalesce, forming an 

 arch, the neural arch, which contains the spinal cord. At the summit of 

 this arch is a spinous elongation, the neural spine. Two transverse processes 

 generally pass outwards from the body of each vertebra, and to them ribs 

 are commonly articulated. 



The caudal vertebrae, or those of the tail, are furnished with neural arches, 

 and spines as in the abdominal region, but well-developed transverse pro- 

 cesses are deficient, while along the inferior surface of the bodies of each 

 vertebra is an arch, similar to the neural arch on its upper edge, and this 



Fig. 3. Skull of the Cod, Gadus morhua. 

 s, p, -Supra occipital ; /, Frontal; n, nasal; p, s, Para sphenoid; p,m, pre-maxillary ; m, max- 

 illary; d, Bentary; I, p're-orbital ; q, Quadrate; 7i,m, Hyo-mandibular; p,o, Pre-opercle; o 3 Opcrcle; 

 s,o, Sub-opercle; i,o, Inter-opercle; c,h, Cerato-hyal; b, Branchiostegous rays. 



lower or haemal arch serves to convey blood-vessels, while from it springs 

 inferiorly a haemal spine. 



Between the neural spines and the -haemal spines certain dagger-shaped 

 bones are inserted along the median lines of the body, and which arc 

 externally for the purpose of attaching the bases of the dorsal and anal fins. 

 The hindmost caudal vertebra, usually of small size, articulates posteriorly 

 with a fan-shaped bone, the hypu-ral, which along with the last neural and 

 haemal processes support the caudal fin. Among the plagiostomes the 



