OF A SILUROID; S. HIROTA. 3^9 



The appendage occupies a comparatively wide space behind the 

 urogenital papilla and is so situated as to be more or less protected by 

 the paired pelvic tins. It is very soft and pliable, and is in its natural 

 state blood-red in colour. It is, as a whole, divided into two sym- 

 metrical halves, each of which is asrain subdivided into numerous thin 

 lobes of various sizes. Figs. 3-5 represent three ditterent aspects of 

 one and the same specimen : Fig. is the dorso-anterior. Fig. 4 the 

 ventral, and Fiir. 5 the dorsal, view. Tlie whole oro\an is lod^red 

 in a depression (Fig. 2) of the Iwdy proper, corres[)onding in shape 

 to the dorsal surface of the organ, in <a manner represented in Fig. 10. 

 On a ventral view, the urogenital papilhi anteriorly, and the front end 

 of the caudal fin posteriori}^, are received between the two divisions 

 of the appendage. At the bottom of the depression just men- 

 tioned, there is a collar-like structure {collar Fig. 2) surrounding a 

 central pit (marked fissure, Fig. 2). Into this pit is inserted the stalk 

 of the appendage by which it is connected with the body-proper and 

 which is situated rather nearer the anteri(3i' end of the orf^an. There 

 is between the stalk and the collar a distinct canal all around except 

 at the anterior median line where the stalk is adherent by a narrow 

 strip to the urogenital papilla. The size of the appendage may 

 vary in different individuals of the same stage. The largest found 

 among about four dfjzen specimens of adult individuals is 8 mm. in 

 length and 12 mm. in breadth, wdiile the individual to which it 

 belongs measures 180 mm. in total length. 



If we examine a lobe or leaf of the appendage under a magnifying 

 lens, Ave observe numerous more or less round deep pits of different 

 sizes on its surface (Fig. G). Examined in a fresli state, these pits are 

 found to be in meshes of a fine net-w^ork of ca})illaries as represented 

 in F\<r. 7. Also in the same state numerous branchin"" blood-vessels 



a CD 



are seen in the interior, (Fig. 11) although they are rather obscure in 



