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permits some movement up and down, but very little from side to side, the latter being 

 rendered even more difficult by the stout transverse processes on the 2nd to the 4th vertebræ 

 being bound by means of dense connective tissue with some keeled scales, which are con- 

 siderably larger and especially longer than the remainder of the external covering. In this 

 way movement between the first 4 vertebræ is also considerably reduced. The interspinous 

 bone of the long spine is not so long and scarcely so stout as the spine itself; it is a dagger- 

 shaped, almost rounded bone, with two grooves, in front and behind, for muscular tendons. 

 It is well-supported at the base owing to the fact, that the part which extends up over the 

 spinous process of the 3rd vertebra is connected with a (rayless) interspinous bone, which 

 is provided laterally with a pair of low muscular crests in the form of a rounded ridge, the 

 lower end of which is wedged in between the spinous processes of tiie 2nd and 3rd vertebræ 

 and even reaches to the vertebral arches. A similar, but slightly weaker (raylessi intersjiinous 

 bone is found between the 1st and 2nd vertebræ, and a similar, but mucii weaker interspinal 

 rests against the anterior face of the spinous process of the Ist vertebra and above sends 

 forwards a process, which is connectetl by means of a short and tough, ligamentous connec- 

 tive tissue with a similar process on the supraoccipital. The whole of this narrow bony 

 plate formed by the rayless interspinous bones is flexible, but the single pieces are not arti- 

 culated together; the interspinous bones themselves are connected by a kind of "harmonia" 

 and their upper, thickened margins are united by a kind of suture. — In agreement with 

 this, the connections between the first 4 vertebræ are but little movable, as their arches (and 

 articulating surfaces) are kept in place over a fairly long distance by a kind of "harmonia". 

 — The vertebral centra are, as is usually the case where the connections are immovable, 

 slender and of the ordinary hour-glass shape. The intersjjinous bone ends above in 3 com- 

 pressed elevations, one medially and one weaker on each side. The central elevation is 

 thickened at the middle of its upjier edge into a knot, whicli is raised somewhat anil lias on 

 the sides a small pit, into which fits a protuberance or button on the inner side of the deeiily 

 cleft base of the ray. In this way is formed the articulation between the ray and inters])inous 

 bone. — On the lateral faces of the central elevation on the interspinous bone and on the 

 inner surfaces of the deeply cleft base of the ray there are about ten circular, sharp-edged 

 keels (fig. 16), which lit into one another and are shiny (as if polished) at the margin and on 

 the one side: the keels of the interspinous bone on the surface directed upwards, those on 

 the ray on the downward surface. On the outer sides of the deeply cleft base of the spine 

 and on the inner side of the two outer elevations on the interspinous bone there are similar 

 keels, but only a few and much weaker. 



Musculature. F'or the long spine there are the usual 2 jiairs of muscles; the M. ante- 

 riores, which are much stronger than the M. posteriores, fill the space between the interspi- 

 nous bone and the rounded muscular ridge on the preceding (rayless) interspinous bone. 

 Both pairs are provided with long tendons, which are attached somewhat high up on the ray. 



In the dead fish the long spine is so fixed that it cannot be moved, neither by means 

 of its muscles nor by the fingers without using force. After I had observed the above de- 

 scribed, circular keels and their nature, and thus learnt that the fixing depends on the down- 

 ward pressure of the ray on the interspinous bone, I was able to unfix the joint by raising 

 the ray and at the same time giving it a circular turn, just as was the case with the earlier 

 described Triacanthus. The ray is most probably fixed by the simultaneous action of the 

 M. anteriores and posteriores. — The specimens were too small to determine whether the 

 portions of connective tissue, which occur between the spine and the interspinous bone, 

 either the front part or that at the joint, serve to undo the latter, similar to what occurs in 

 Triacanthus; how the fish itself unlocks the joint is thus unknown". 



In different recent authors, such as Copk, Jordan and Evermann, Bkan and (îoode, Starks, 



