VERTEBRAL COLUMN. 



15 



The abdominal or trunk 

 vertebra) have two superior 

 or dorsal processes, which 

 passing upwards coalesce and 

 form an arch (»a), termed 

 the neural arch which protects 

 the spinal chord. At the 

 summit of this arch the bones 



join and form a spinous elon- 

 gation, the neural spine (ns). 

 Two epiplcui-al spines (cs) 

 pass outwards from tlie body 

 of each vertebra?, while from 

 either side a rib is directed 

 downwards. 



Fig. 8. Abdominal vertebra of salmon, c. centrum or body : 

 na. neural arch : iis. neural spine: cs. cpipleural spine. 



The caudal vertebra3 (fig. 7) arc furnished superiorly with neural arches, (no) 

 and spines (ns), but well developed transverse processes are absent, Avhile along 

 the lower sui'faces of the bodies of each is a second or the haemal arch (ha) which 

 serves to protect blood vessels, while inferiorlj from this arch springs a hcemal 

 spine (hs). 



Along the median line of the body, between the neural or hcemal spines 

 certain vertically directed dagger-shaped bones are inserted, to which are 

 attached the bases of the dorsal and the anal fins. 

 The hindmost cau- 



dal vertebra, which 

 is of a small size, ai'- 

 ticulates posteriorly 

 with a fan-shaped 

 bone, which alonef 

 with the last few '']J 

 haemal pi'ocesses are 

 similarly enlarged 

 and flattened, and 

 termed hypural 

 bones (%), which 

 support the main 

 portion of the caudal 

 fin. The last two 

 vertebrae are ereuer- 



ally counted as one, 

 a course I shall fol- 

 low, as in specimens 

 when fresh or in 

 spirit it sometimes 

 becomes diflScult to 

 distinguish the line 

 of separation be- 

 tween these two 

 bones. The epipleu- 

 i"al in the embryonic 

 stage is connected 

 with the termina- 

 tion of the noto- 

 chord which lies 

 beneath. 



Fig. 9. Hind end of vertebral column of a 

 salmon, ha. hfemal arch : hs. ha;mal spines : 

 hy. hypural bones : na. neural arch : ?),s. neural 

 spine. 



24 (Os transverse, Cuv.), Pterygoid. 25 (Pteri/gouUen interiie, Cuv.), Entopterygoid. 26 (Jugal, 

 Cuv., Hypotympanic, Owen), Quadrate (Huxley). 27 {Tympanal, Cuv. Pretympanic, Owen), 

 Metapterygoid (Huxley). 28, Opercle. 29, Stylohyal. 30, Preopercle. SI (Jlesotymjyaiiic, Ov;en), 

 Symplectic. 32, Subopercle. 33, Interopercle. 34, Dentary. 35, Articular. 36, Angular. 

 37, Epihyal. 38, Ceratohyal. 39 and 40, Basihyal. 41 (Os linyual, Cuv.) Glossohyal. 42 (Queue 

 de Vos hyolde, Cuv.), Urohyal. 43, Branchiostegal rays. 46 (Surscapulaire, Cuv. Post-temporal, 

 Parker), Suprascapular. 47 (.S'»^;)-«c?ar(CMZa, Parker), Scapula. 48 {Humeral, Cuv. Claricula, 

 Parker), Coracoid. 49 and 50 {Coracoid, Cuv. Postclavicula, Parker), Epicoracoid. 51 {Cubical, 

 Cuv. Coracoid, Parker), Eadius. 52 {Radial, Cuv., Scapula, Parker), Ulna. 53, Carpals. 53 bis, 54, 

 and 55, Basibranchials. 56, Inferior Pharyngeals. 57, Hjijobranchial. 58, Ceratobranchials. 

 59, Upper Epibranchials of first branchial arch. 61, Epibranchials. 62 {Pliaryngohranchial, 

 Owen), Superior Pharyngeals. 68, Abdominal vertebra. 69, Caudal vertebra}. 70, Hyi^urals. 

 72, Rib. 73, Epipleural spines. 74, Interneural spines. 76, First Intemeural. 79, Interhasmal 

 spmes. 80, Pubic. 



t Owen considered that the skulls of these fishes are originally composed from four vertebrffi 

 irrespective of bones of the splanchnoskeleton and dermoskeleton : while Stannius, Parker, and 

 others have arranged them in accordance with their development. 



