Structure of the Short Sun-Fish. 189 



The specimen I had an opportunity of examining was the 

 very large individual lately procured for the Natural History 

 Museum of the University of Edinburgh.* It measured five 

 feet eight inches from the snout to the tail, three feet three 

 inches from the tip of the dorsal to the tip of the anal fin, 

 and weighed four hundred and eighty-nine pounds. 



On commencing to remove the skin, which was found to be 

 rather a difficult operation, in consequence of the total defi- 

 ciency of any structure resembling the dermis, I found that 

 the coloured and tubercular layers of the integuments were 

 attached to the external surface of a structure or tissue of a 

 very peculiar kind. This tissue extended in the form of a 

 layer, varying from one-fourth of an inch to six inches in 

 thickness, all over the body, head, and fins. It was thickest 

 along the median line of the back and belly, of medium thick- 

 ness along the sides, and thinnest on the surface of the fins. 

 Large and thick masses of it enveloped the bones of the cra- 

 nium, and enclosed the opercular laminae and branchiostegous 

 rays. The soft cartilaginous bones were imbedded in such a 

 manner in its substance that they presented the appearance 

 of nuclei in it, and resembled the first traces of the skeleton 

 in the early embryo. The most distant or peripheral elements 

 of the skeleton, the fin-rays, and certain parts of the opercu- 

 lar apparatus, were so much softer and more delicate than 

 the tissue in which they were imbedded, and so completely de- 

 ficient in any periosteal covering, that they could only be dis- 

 covered in the fresh state by their translucency. 



This peculiar tissue was separated from the muscular sub- 

 stance in its neighbourhood by the ordinary loose filamentous 

 structure (cellular membrane). Its relation to the skin was 

 very peculiar, and will be explained after the structure of the 

 tissue itself has been described. The tissue was inelastic, 

 tough, of a dead white appearance, resembling lard, granular 

 when torn, and presented very slight traces of vascularity, and 

 these only in the neighbourhood of certain parts of the skele- 

 ton. It discharged no oil, but on standing a quantity of watery 



* Tliis specimen was found in shallow water in the Frith of Forth at 

 Culross, lying Bluggishly on one side, but making vigorous resistance when 

 attacked. 



