204 DR. W. N. F. WOODLAND ON THE 



actdeatus have been described and figured by Coggi (25) ; Gaster- 

 osieus aculeatus has also been described and figured by Deineka 

 (29) ; Blennms, Gobius, Syngnathus, and other types have been 

 briefly described by Reis (64). All these " red bodies" evidently 

 belong to the Syngnathus type as defined above. 



A Third Type of Bladder Vasculo-glandular Apparatus, 

 as exemplified in Ophidium barbatum L. 



The " red body " of Ophidium barbatum has received a con- 

 siderable amount of attention during the last few years, especially 

 from the cytological standpoint (Bykowski & Nusbaum, 24 and 

 Reis & Nusbaum, 62, 63), since the huge cells composing the gas 

 gland offer exceptional facilities for enquiry in this direction. 

 But, as in some other instances, good figures of the gross anatomy 

 do not exist, so far as I am aware, and hence I shall make no 

 apology for recapitulating already-known facts in a manner that 

 shall be intelligible to the reader who has not worked at the 

 subject. 



The " red body '' of Ophidium barbatum is situated anteriorly 

 in the ventral wall of the bladder and has the curious appearance 

 shown in figure 48(P1. YL). The fan-shaped deep red portion is, of 

 course, the rete mirabile, which is here an undivided body, and it is 

 formed by an artery and vein which enter at the pointed posterior 

 apex. The pink margin surrounding the anterior border of the rete 

 is, obviously, the gas gland, A transverse section i-unning mid- 

 way through the " red body " exhibits the parts diagrammatically 

 indicated in figure 49 (the outer layers of the bladder have been 

 stripped off). In the centre is the rete mirabile and at the sides 

 are the enormously thiciiened glandular portions of the (elsewhere) 

 flattened lining epithelium. As in some former instances, there is 

 no reunion of the capillaries of the rete mirabile before supplying 

 the glandular epithelium : they directly supply the gas gland. 



Kow in this type of " red body "' the gas gland does not consist 

 of a single layer of cells which has become folded, but of a many- 

 layered mass of cells, the arrangement of which bears no resem- 

 blance to the folded condition of the single-layered epithelium of 

 the " red-bodies " already described (see figs. 54, 58, 63 for 

 examples of the massive tj^pe of glnndj, and, judging from the 

 development of this massive type of gas gland epithelium as seen 

 in Atherina, it never does, at any stage of its development, bear a 

 resemblance to the folded type of gland. The many-layered or 

 massive kind of gas gland epithelium, as seen in Ophidiimi, 

 Atheri7ia, and other genera to be mentioned, is, then, a distinct 

 type ; the question raised bv Reis in a recent paper (64) as to 

 whether there exist forms of bladder epithelium transitional be- 

 tween these two types is one which I shall discuss when describing 

 Atherina. The faintly-granular cells composing this m.any-layered 

 gas gland of OphidAum are of quite moderate dimensions in the 

 vicinity of the rete mirabile, but become larger the further they 

 are removed, and the cells at the remote edge of the gland are 

 remarkable for their large size, In this type of gland there exist 



