GAS GLAXDS OF SOME TELEOSTEAN FISHES. 209 



about twelve cells deep, is nu example of the massive tyjie 

 possessing a stiuamous lining epithelium. The lumina consist of 

 small crack-like spaces visible here and there between the cells 

 (largely arranged in vertical rows) in ti-ansverse sections 

 of the gland, and they form a system of fine anastomosing 

 channels opening at A^arious points on the surface into the 

 bladder lumen. Gas bubbles were occasionally to be found in 

 the gland cells. I did not observe any intracellular capil- 

 laries, but they doubtless occur; intercellular capillaries, on the 

 other hand, are extremely plentiful and occur largely near the 

 extreme edge of the glaud underlying the layer of flattened 

 cells. The glandular epithelium of Coris julis difiers from 

 preceding examples of the massive type in that the cells lying 

 next the bladder cavity foim the squamous layer, or in places 

 layers, just mentioned. 



It was doubtless because Corning (28) chiefly examined " red 

 bodies " of this extreme massive type, as e. y. that of the Pike, 

 that he concluded that the bladder glands possess no lumina, and, 

 indeed, were it not for our knowledge that most bladder glands 

 possess lumina and that these vary greatly in volume according to 

 the state of activity of the gland, we should pi'obably come to the 

 conclusion if studying exclusively the same mateiial. 



CORVINA NIGRA Cuv., SaeGUS RONBELETIl C. V., BaLISTES 



CAPRiscus L., Caranx trachurus and Serranus cabrilla L. 



The "red bodies "of these genera all belong to the massive 

 epithelium type, although they vary in a^ppearance macroscopically 

 (Pis. VII. (fc VIII. ligs. 59-61) in correspondence with the vaiying 

 configuration of the rete mirabile. The " red body " of Batistes 

 alone is situated near the posterior end of the ventiul wall of the 

 bladder. In all cases the glandular epithelium has the usual 

 structure — a thick mass of cells, penetrated by large or small 

 intercellular and intracellular lumina and capillaries. 



Zeus faber L. 



The " red body " of Zeus faber is of the curious form depicted in 

 figure 62 (PI. VIII.), and occupies the anterior half of the ventral 

 surface of the bladder wall. It has already been figured by Vincent 

 & Barnes (75). The " red body " consists of two lateral divisions, 

 each division being shaped like a C divided into three parts, and 

 its concavity facing that of its companion. The primary artery 

 and vein enter at about the centre of the " red body " and supply 

 branches to the retia mirabilia lying on the inner sides of the gas 

 gland thickenings. Anteriorly to the " i-ed body " a thick median 

 longitudinal muscle- band is developed in the ventral bladder wall. 

 The glandular epithelium of the John Dory is of the ordinary 

 massive type, though more folded in appearance than is usual. 

 It is significant that Vincent & Barnes, who wished to reduce 

 all " red body " glandular epithelia to the folded type, remark 



