16 



43. Three vertebrae of the Conger Eel. Hunterian. 



44. Several abdominal and some caudal vertebrae of an Eel; showing the pro- 



gressive bifurcation of the parapophyses at the beginning of the tail, the lower 

 forks descending and forming the sides of an open haemal canal, like that in 

 the tail of Serpents (see No. 26). Hunterian. 



45. The left ramus of the lower jaw of the Electric Eel (Gymnotus electricus) : it 



supports a single series of small, equal, triangular, compressed, recurved and 

 sharp-pointed teeth. Hunterian. 



Suborder II. ABDOMINALES. 



46. The skeleton of a Bull-trout (Salmo eriox, Linn.). It is of a male, with the up- 



turned cartilaginous prolongation or appendage of the lower jaw, character- 

 istic of the sex : its weight when caught was 22 Ibs., and the skeleton 

 measures 3 feet 4 inches in length. Number of abdominal vertebrae, 28 ; of 

 caudal vertebrae, 32 : total, 50. 



The neurapophyses have not coalesced with the centrum in the anterior abdominal ver- 

 tebra, nor do they blend with each other until the last abdominal vertebra. In the pre- 

 ceding vertebrae each neurapophysis is produced into a long and slender spine, and the neural 

 spines in these vertebrae thus appear to be double, or in transverse pairs. The epineural 

 rays begin to be developed from the second, and are continued to the antepenultimate, abdo- 

 minal vertebra. They diverge outwards and backwards from the base of the neurapophysis *. 

 The neural arch again becomes distinct from the centrum in the last six caudal vertebrae, 

 and the penultimate one has its base unusually extended, both forwards and backwards, so 

 as to clamp together the four terminal vertebrae. The neurapophyses have not united to- 

 gether above the neural canal in any of these vertebrae. The three terminal vertebrae with 

 neurapophyses, and the last rudimental one, which consists of the modified centrum, bend 

 upwards, and manifest, with the different proportions of their neural and hcemal arches and 

 spines, a certain retention of the primitive heterocercal structure. 



The last caudal vertebra departs, like that which commences the vertebral column, from 

 the typical cylindrical form of the centrum, and beyond its articulation with the penultimate 

 centrum becomes compressed and vertically expanded, and transformed into a triangular bony 

 plate, embraced by the split proximal ends of five or six of the caudal rays. The first and 



* These diverging rays, are the superior costae or ribs, ' obere rippe,' of Meckel and other German 

 anatomists. 



