49 315 



Endoskeleton. 



The vertebral column (PI. VII, fig, 3) is composed of 33 vertebræ, 19 ab- 

 dominal and 14 caudal. Ribs are wanting. The 3 anterior vertebræ are sutur- 

 ally united, the remaining only connected by means of the corpora, no articular 

 processes being developed. 



The 5 anterior vertebræ are larger and stouter than the rest, especially the 

 2nd and 3rd are large; from the 6th the vertebræ decrease in size backwards, only 

 the last being again somewhat enlarged and together with the last but one 

 expanded into a large vertical plate supporting the rays of the caudal fin. 



Strong anterior articular processes on the 1st vertebra overlap corresponding 

 processes on the exoccipitals, allowing the skull to be moved vertically. The ten- 

 dons for the muscles which raise the head are ossified (as in Fistularia, Aulosloma, 

 Nerophis ophidioii), forming on each side a large flat bone, in front fastened to tlie 

 epiotic, behind dissolving into numerous fine threads (PI. Ill, fig, 10 Id). Posteriorly 

 the 1st vertebra is immovably joined to the 2nd by means of strong denticulations, 

 and in the same way the second joins the third. Spinous processes are devel- 

 oped on all the vertebræ. Transverse processes are wanting on the anterior 4 

 and only indicated on the 5th; from the 6th on all the remaining abdominal 

 vertebræ show a well-developed transverse process, increasing in size backwards 

 and becoming more and more directed downwards; on the first caudal it joins 

 its fellow from the opposite side forming a strong laterally compressed inferior spine. 

 No "secondary" transverse processes occur on any of the vertebræ. 



The superior and inferior spinous processes on the 9th or in another speci- 

 men the 10th caudal (the 28th or 29th vertebræ) are almost vertical, those on the 

 following inclined or bent forwards; this position is apparently due to the extreme 

 development of the parts supporting the caudal fin. On most of the vertebræ a 

 process occurs from the base of the neural arch behind the spinous process and 

 a similar one ventrally in the corresponding position (i. e.: on the abdominal ver- 

 tebræ behind the transverse process, on the caudal behind the inferior arch). On 

 the penultimate caudal vertebra these processes are fused with their fellows from 

 the opposite side, distally expanding into a large, laterally compressed plate. Pro- 

 bably the still larger plate surrounding the last vertebra is made up of corre- 

 sponding elements fused with the true upper and lower spines and the hypurals. 

 To elucidate the exact composition of this ray-supporting apparatus an examination 

 of sufficiently young specimens would be necessary. That the extraordinarily large 

 size of the caudal plate is caused by the great development of the fin is very evi- 

 dent and needs no further explanation. 



If we compare the vertebral column with that of the Syngnathidæ the chief 

 points of resemblance seem to be the intinuite connection of the 3 anterior verte- 

 bræ and the absence of articulations between the neural arches of all the other 

 vertebræ; in general shape there are no obvious resemblances, neither with the 

 Syngnathidæ nor with Fistularia, Aulosloma or Centriscida: 



I). K. n. Vidensk. Selsk. .Skr.. 7. Række, nnturvideiiNk. üg iiiatUeiii. At'd. \'II1, ."i. 41 



