24 Msher// Board for ^Scotland. 



Figs. 66 and 85). Sometimes a slender urinary papilla is present in the 

 female, e.g., in an immature fish 24 cm. long-. In another fish the 

 papilla was flattened and had a fringe along two sides (Fig. 75). The 

 fringe in a female which had developing embryos in the ovary was 

 large {ur.fr., Fig. 73). In May the fringe was observed to be red, 

 suffused with blood. In the case of one pregnant female (May), a 

 red tube (?) projected from the oviduct. The filament which is 

 shown projecting from the oviduct in Fig. 85 may have been acci- 

 dentally torn from the wall of the oviduct. An enlarged drawing of 

 a fringe is shown in Fig. 66. Its ventral surface was deeply ridged, 

 especially so in the proximal half (fo.). It was less prominently ridged 

 at ri. It ended distally in translucent processes between which the 

 urethra opens. The upper surface of the fringe is practically plain. 

 This organ probably acts as an aerating organ in connection with the 

 developing embryos in the ovarj-. 



A very marked difference exists between the two sexes in the size 

 of the iirinary bladder. This is seen in Figs. 62 and 63, which repre- 

 sent the abdomen of the male and female fishes in natural size. The 

 urinary bladder of the male is enormous, {iirbl. Fig. 62). The urinary 

 bladder is a tNvo-laj'ered sac ; the layers can be easily torn apart. 

 The external coat of the bladder is usually grey or black, on part of 

 its surface at least. The inside wall is deeply honeycombed and well 

 supplied with blood-vessels. The bladder usually contains a cream- 

 coloured or yellow fluid, in great quantity in the male, in small 

 quantity in the female. The fluid, which is probably secreted by the 

 bladder, is albuminous ; it coagulates on the addition of water. Under 

 the microscope it is seen to contain corpuscles and oil drops of various 

 sizes. In the male the fluid issues by the apex of the papilla (itrth.), 

 while the sperm finds issue by a pore on the anterior side of the apex 

 (v.d., Figs. 89 and 90). The vas deferens is a wider channel than the 

 urethra. The fluid is j)robably injected into the ovary along with the 

 sperm, when impregnation takes place. 



Develoijmeni of the Testis. 



In December, January, and February ripening testes are found. 

 The urinary bladder is very large. In January and P^'ebruary ripe milt, 

 which ajDpeared to contain spermatophores, or groups of sperms, was 

 observed. One male had in its urinary bladder during February a 

 fluid that more nearly resembled water than the usual thick j'-ellow 

 fluid. Two of the testes were in this month apparently spent. 



In March, April, May, and June the testes were all small. The 

 urinary bladder varied in size, but usually contained yellow fluid. In 

 two cases a collapsed bladder was found. Some of the small testes 

 were no doubt spent. In July and August the small testes showed 

 signs of beginning to ripen. 



The testis was in September and October usually large and white 

 in colour. The urinary bladder was large. Impregnation probably 

 takes place in January and Februarj^. 



Developnie7it of the Ovary. 



The ovaries are separate (Fig. 85) ; the oviducts unite {j ). The 

 ovary is pigmented black, or a dark grey, externally. The pigmenta- 



