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Show 338 LIEUT. ANNESLEY ON GONODACTYLUS CHIRAGRA. [June 1 2, which, similarly to that on the dorsal outline of the skeleton, unites the extremities of the interhaemals, extending from the end of the anal to the pubic bones, and forming a complete but feeble ring round and supporting the abdominal cavity. The pubic bones are very short and coalesced, but slightly divergent behind, so as to leave a narrow opening for the vent, which can be entirely closed by the rudimentary and coalesced but ossified ventral fins, which serve in this fish as a sphincter ani. The formula of fin-rays of this specimen are:-D. 13. A. 14. C. 7+164-6. P. 15. 4. Notes on the Habits of Gonodactylus chiragra. By Lieut. O. F. T. A N N E S L E Y , B.A. (Communicated by Dr. J. E. G R A Y .) In May 1865, while stationed at Aden, I caught by a small hand- • dredge in a rock-pool an animal which I have since learnt is most probably the " Gonodactylus chiragra," and for rather more than a month I kept it, sometimes in a small tumbler, sometimes in a large glass lamp, one of those which are occasionally used in halls, hanging from the ceiling, and which when arranged form by no means a bad aquarium. The colour of the animal, which was of a brownish yellow, has greatly faded since its death. Perhaps what strikes one most is the two curious prehensile claws with which the creature is provided. These are, I believe, used as instruments of defence and offence, and are really most powerful weapons. The animal seems to possess the power of darting them forward with very great force ; and so beautifully are they constructed that they appear never to suffer any injury, however hard may be the substance against which they are driven. I have not forgotten how I first became acquainted with the fierce propensities of the animal. I was moving one of the objects in the aquarium with a long pencil; in doing so I passed the pencil along the bottom near the animal, which, without further provocation, darted at it, nearly striking it out of m y hand and astonishing me not a little. And afterwards, whenever the pencil was moved towards it, the animal invariably attacked it furiously; in fact I think his temper grew worse from our continually provoking him. Frequently when sitting at the end of the room I have heard repeated knocks against the sides of the glass, occasioned by the attacks of this animal against the harmless Ophiuri, who, when travelling round the sides of the aquarium, inadvertently touched him with one of their curious rays, which, though composed of hard calcareous matter, were always severed by a single blow from the claw of the Gonodactylus. For the sake of experiment I enclosed an Ophiurus (each of whose rays measured about 4 inches) and the animal in a tumbler, when the |
