. Text-fig. 8. Fat-invested swimbladder of Cyclothone braueri. bk, bulbous, posterior part of kidney; ft, fatty investment of regressed swimbladder; oy, ovary; pv, pelvic fin; rsb, regressed swimbladder. ( x 18-9.) As the larvae of Cyclothone braueri have a gas-filled swimbladder, it is clear, as previously men- tioned, that the organ gradually regresses and receives a thick coating of fat during the adult phase. Nusbaum-Hilarowicz (1920) studied the histology of the swimbladder of a species of Cyclothone, under the name C. signata, but in view of Jespersen's and Taning's (1926) critical work,
. Text-fig. 8. Fat-invested swimbladder of Cyclothone braueri. bk, bulbous, posterior part of kidney; ft, fatty investment of regressed swimbladder; oy, ovary; pv, pelvic fin; rsb, regressed swimbladder. ( x 18-9.) As the larvae of Cyclothone braueri have a gas-filled swimbladder, it is clear, as previously men- tioned, that the organ gradually regresses and receives a thick coating of fat during the adult phase. Nusbaum-Hilarowicz (1920) studied the histology of the swimbladder of a species of Cyclothone, under the name C. signata, but in view of Jespersen's and Taning's (1926) critical work, the species is most likely to be C. braueri. The figures and description show that the swimbladder of this fish was in much the same developmental phase as the 26-5 mm. individual described above. Cyclothone livida Brauer St. 3094, 440 20'N., i6°49'W., 21. v. 54, TYFH, i50o(-o)m. Standard length of two fishes examined 55 and 37 mm. In both these individuals the swimbladder has much the same position in the body-cavity as that of C. braueri. It is sausage-shaped, having a length of about 5 mm. in the larger fish and about 4 mm. in the smaller one. The middle diameter in both is about 1-5 mm. Under the layer of black peritoneum that invests the swimbladder come the silvery or faintly golden globules of the fatty tissue. This entirely fills the swimbladder and, as in C. braueri, the fat droplets are held in a rather wide meshed reticular connective tissue. In the middle of the swim- bladder is a cream-coloured body receiving blood-vessels entering the posterior end of the organ. The swimbladder of the larger fish was taken for transverse sectioning and the following extra details of structure seen. At its posterior entry and for most of its course to the regressed gas-gland, the blood system consists of six small vessels bound closely together. Three arterioles each have an
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