6814 Fishes. 



two limbs, as already described, uniting at an angle in the centre. The same muscu- 

 lar action which draws back ttie point of junction in drawing it downwards, and away 

 from the lower jaw, widens the whole extent of the pipe-like mouth ; but it does more 

 than this, for by the same action the two lips of the bony fork, or derrick, are made 

 to diverge, and in so doing the throat of the fish is also enlarged laterally and to 

 double its former size. In an ordinary-sized Syngnathus, the lower jaw measures 

 about a quarter of an inch across, when the bony fork is lying in its receptacle, but 

 when the fork is in action and out at its full extent at right angles to the jaw, 

 its limbs diverge until it separates the jaws to the extent of half an inch. The 

 Syngnathus may be watched a long time in confinement before the action of this ap- 

 paratus is seen. Sometimes one's patience is quite worn out watching for it; at other 

 times the action is seen several times in a minute, and it is then beautiful to observe 

 with the action and projection of the bony derrick the simultaneous drawing down of 

 the lip and the widening of the long pipe-like mouth and throat. In this mechanism 

 there is an antagonism of ligamentary and muscular action, the ligamentary elas- 

 ticity drawing down and retaining the point of the bony fork in its receplacle within 

 the angle of the jaw, the muscular action elevating it when required to aid the action 

 of swallowing. In the dead animal the elastic action containing the bony fork is re- 

 tained in its receptacle, and escapes observation. In the living animal, however, 

 this bony process and its action may be easily demonsirated, by gently bending 

 back the head of the fish, and raising the point of the process with the nail or a fine 

 edge, and it will then be seen that while thus retained the mouth is opened wide and 

 cannot be shut. Dr. Mayue has drawn my attention to an antagonism of muscular 

 action and ligamentary elasticity in the larynx of the porpoise, similar to that which 

 exists in the jaw mechanism in the Syngnathus. In the porpoise an elastic action 

 keeps the larynx closed without any efi"o!t on the part of the animal until it rises to 

 breathe at the surface, when a muscular action comes into phiy, and fur the moment 

 opens the larynx to permit the ingress of air. The Syngnathus is one of our most 

 interesting fishes in a vivarium, so singular in appearance, so different from all other 

 order of fishes, and so vivid in the contrast of its colours, and so cased in armour. 

 It is at first very wild, and, unless the vivarium be covered, will almost certainly jump 

 over its sides; but it soon becomes reconciled to confinement, and will, with a turn or 

 two of its tail, support itself on any stem placed in the vivarium for its support; or, if 

 there be two of them, they will intertwine their tails in a knot, and raise their heads 

 and long slender bodies, side by side, towards the surface, remaining for hours in that 

 posture. In this (the Syngnathus sequoreus) there is no pouch for the reception and 

 protection of the young ; but in the other specimen on the table (Syngnathus acus), 

 which I beg also to present to the Society, the pouch — if it can be properly called a 

 pouch — is well seen. It is about four inches long, resembling a bag split down one of 

 its sides, and with the edges lying in apposition. I must beg of the Society to excuse 

 any errors into which I may have fallen in my observations, for my acquaintance 

 with Natural History is necessarily very limited, but it happens that I have occa- 

 sionally favourable opportunities of observing the physiology and habits of some of 

 our fishes in confinement, and such observations as I have in my power I feel 

 obliged to this Society for receiving. — Dr. Carrigan, addressing the Dublin Na- 

 tural History Society. 



