444 Survey of Fishing- Grounds, West Coast of Ireland, 1890—1891. 



the lower surfaces of the bodies of the 6th, 7th, and 8th vertebrfe, but not 

 enveloped by bone. The larger portion is comparatively simple, but wide and 

 capacious, being fully two inches at its broadest. It has towards its anterior end 

 an imperfect horizontal septum, forming an upper and lower compartment. The 

 upper ends blindly, the lower communicates with the canal leading to the 

 anterior portion of the bladder. The lower wall bears two circular rete mirabile 

 below the posterior end of the septum. These are placed one behind the other, 

 and the more anterior one has, immediately above it, a circular opening in the 

 septum, so that, when the bladder is not fully inflated, it can pi'oject into the 

 upper horizontal compartment. At the extreme posterior end of this portion of 

 the bladder there is another rete mirabile, formed so as to fit what may be termed 

 the fundus of the bladder. The anterior portion of the bladder is first of all 

 completely divided into two sections, as seen in the figure. The lower section is 

 formed by an extremely delicate membrane, and appears, when looked at from 

 the ventral aspect, to be laid upon the under surface of the firmer and more 

 important section of the bladder. The attachment of the membrane, however, 

 is found to be fibrous and well defined, while the anterior half bears a flattened 

 disc-like rete on its lower surface. The upper section may be said to be naturally 

 divided into two lateral cavities by the anterior portion of the vertebral column, 

 and by the occipital region of the skull. Those cavities communicate with one 

 another at their posterior ends by a passage under the vertebral colimin. The 

 figm-e shows only the cavity on the right side of the head, a diagrammatic 

 outline of the bladder as seen from above being given in fig. A'. Each lateral 

 sac is attached by strong fibrous bands posteriorly to the body of the 5th vertebra, 

 and anteriorly to the posterior surface of the pterotic bone. 



A median attachment is also secured to the first five vertebrae of the column 

 and to the basi and exoccipital bones. 



Each lateral cavity may, therefore, be spoken of as passing forwards, upwards, 

 and outwards from below the level of the fifth vertebra, under both branches of 

 the post-temporal bone, between the supra-scajDula and the exoccipital bones, to the 

 posterior surface of the pterotic. The passage leading from the cavity of one side 

 to that of the other has situated in it three circular rete mirabile, and is, in the 

 specimen figm-ed, of sufficient size to admit the little finger. Into this passage the 

 canal leading from the larger or posterior portion of the bladder opens. At no 

 part of the air-bladder is there any pneumatic duct in connection with the 

 alimentary tract. 



The kidneys remain to be mentioned. They are situated in the norma] 

 position, immediately superior to the swimming-bladder, but as in other deep-sea 

 fishes are much prolonged. There are two distinct head-kidneys which could not 

 be shown in the figure, as it was necessary to dissect the right one away, along with 



