274 8 



Like the preceding modified interneurals they all consist of only one single piece 

 (are "unisegmented"); in position they are about horizontal. The interneurals 

 supporting the second dorsal fin number 26 or 27; except the foremost and hind- 

 most they are "bisegmented", a small ossicle (with a median cartilaginous centre) 

 occupying the cleft base of each ray and connecting through cartilage with the 

 main part or stem. The foremost interspinous bone is small and rayless, the next 

 two support quite rudimentary rays. The two anterior are together interposed 

 between two spinous processes (of the 34th and 35th or 35th and 36th vertebræ), 

 but only tlie second almost reaches the spine; the following ones are interposed 

 singly or in pairs (somewhat irregularly); from the sixth they reach almost to the 

 base of the neural arch, from the twelfth almost to the corpus; the hindmost 

 again are shorter. 



The anal fin is supported by 26 interspinous bones, likewise bisegmented. 

 The anterior bones slope forwards, the foremost is about horizontal in position; 

 the fourth reaches the spinous process of the 35th (or 36th) vertebra, lying close 

 behind the tip of its inferior spinel 



The fin-rays of the unpaired fins. The isolated dorsal rays are 

 spines (PI. II, fig. 10, s), made up of one piece, without any joints; they are rather 

 blunt, flat and somewhat weak, basally with a transversely rounded head, articulating 

 with a transverse pit in the inlerneural ^. 



The four anterior rays of the second dorsal are also pointed, unjointed like 

 spines; the foremost two are rudimentary and both supported by the second inter- 

 neural. The following rays are longitudinally cleft and jointed, but not branched 

 distally. 



Of the anal fin (29 rays) the 4 anterior similarlj' are short, spine-like, the 

 rest like those of the second dorsal. 



The caudal fin has 20 rays: 3 -f~ 7 + 7 + 3; the three upper and lower 

 rays short, pointed and without joints, the rest jointed ; No. 5 to No. 15 are distally 

 branched. 



Closer examination of the skeleton of the end of the tail shows that two 

 separate bones are interposed, like interneurals, above between the last vertebra 

 and the last but one, and in a similar way also two bones below; but of the two 

 lower the hindmost seems to be fused with the lower hypural bone of the last vertebra. 

 The rays are arranged in the following way: the foremost short ray is interposed 

 between the spinous processes of the third and second last vertebra; the two fol- 

 lowing short rays and the first upper jointed ray are supported by the "interposed" 

 bones; the upper hypural bone carries 6 rays, the lower 5 or 6; of the rest of the 

 lower rays, two jointed and two unjointed are supported by the lower "interposed" 

 bones, the anterior short ray is correspondingly situated to the anterior upper one. 

 As mentioned above only the rays 5 — 15, i. e. those supported by the hypural 

 bones, are distally branched ; of these the two middle ones — one from each 

 hypural — are somewhat longer than the rest, causing the rhomboid outline of the 

 caudal fin (probably homologous to the caudal filament in Fistularia). 



