TRANSACTIONS OF SECTION D. 739 



hardened secretion, but liow and where this secretion, or perhaps better, excretion 

 is formed is not known. 



A clear, glistenins^ substance of varnish-like consistency, which covers the 

 torpid animal within the capsule and keeps it moist is probablj' of the same nature. 

 This calls to mind the arrangement for protecting the young in Epicrium described 

 by the two Sarasins. 



The hard external covering may also partiallj- perform a similar function, but it 

 serves chiefly to protect the animal from compression during the gradual contrac- 

 tion of the enclosing earth in drying. 



Giintherlias observed a mucus-secreting apparatus in Cerato(lu,s,yvh.\ch. opens to 

 the exterior near the articulation of the lower jaw, but it is not known whether a 

 similar structure is present in Prof.optei'us. 



The position of the animal during its long period of torpor is very peculiar, and, 

 as I believe, has not yet been described. I add the following exact details. At first 

 sight it is impossible to distinguish the different regions of the body, the animal 

 simply appearing like a mass of irregular form, the spaces between its individual 

 parts being filled up by the glairy secretion. 



With careful examination, however, it is possible to distinguish the snout, 

 which is enclosed by a broad membrane covering the whole head like a veil. This 

 membrane, which is covered with spots of pigment, is the broad tail-fin, which, 

 gradually narowing as it passes backwards, ends in a whip-lash-like filament. 



This caudal filament lies close against the left side of the body, near the point of 

 origin of the hinder extremity, and from here it becomes curved upwards towards 

 the anterior boundar}' of the dorsal fin. At this point the body is sharply bent on 

 itself towards the right side, and the angle thus formed corresponds to the position 

 of the filament described by Bartlett as arising from the capsule and passing 

 through its entire diameter from above downwards. 



The body then curves forwards and passes into the tail, which, as already 

 described, covers the head and anterior part of the trunk. The ends of the two 

 anterior extremities project forwards like the ' horns ' of a snail between the snout 

 and the overlying dorsal fin. 



During the removal of the capsule the animal remained perfectly motionless, 

 and only began to move convulsively on being irritated. 



After being put into water an hour passed before the animal was completely 

 unrolled, and during this time the glairy mucus was drawn out into white 

 threads. 



At first the head was gradually pushed out from under the tail-fin, the move- 

 ments being very slow, and reminding one of the manner in which a snail extends 

 itself out of its shell. 



This is the only possible method for the animal to begin unrolling itself, for the 

 caudal filament is so firmly fixed to the body-wall that it can only be loosened 

 after the whole of the rest of the bod}' is set free. 



Soon afterwards bubbles of air, and then water, could be seen passing out of 

 the gill-opening, and then the animal began to swim about, seeming at once to be 

 quite at home in the water. 



Both specimens are still living in the Anatomical Institute at Freiburg. 



In conclusion I must mention two circumstances in connection with the physio- 

 logy of Protopterus during its torpid state, which seem to me of great interest. 



In the neighbourhood of the snout I found a soft greyish-white mass, which 

 had evidently been excreted by the animal. This resembled the excretion of birds 

 and reptiles, and I have no doutt that it is to be explained in the same way, and 

 that the vital functions of the animal go on slowly during the whole period of 

 torpor. As this mass is deposited close to the small aperture in the capsule, it is 

 very probable that the latter serves to conduct it to the exterior. 



I cannot decide with certainty whether this aperture, as former observers have 

 supposed, serves also for respiration, but I am able to show that Protopterus 

 possesses a special respiratory orf/an in its broad tail-jin. 



Over the head and for some distance backwards, where it lies close against the 

 external wall of the caps'ole, the tail-Jin was of a bright red colour, and an examina- 



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