ST U I iG E O N -El S H E S . 
1053 
the lateral anterior margin of the right lobe; and the 
gall-duct ( ductus choledochus communis ) opens on the 
right side of the above-mentioned pancreatic orifices. 
The spleen (/), about 137 2 cm. long and S l / 2 cm. broad, 
is pointed behind and forked, being divided from in 
front, throughout the greater part of its length, into 
two anteriorly pointed lobes, the lower of which lies 
under and to the left of the above-mentioned first crook 
of the stomach, behind and projecting a little way over 
the pancreas, while the other lobe is laid to the right 
of the mesenterial fold joining the stomach to the intes- 
tine. The testes ( ts and td) of the present specimen, 
which was taken in the middle of July, are very tumid, 
and had nearly attained their annual ripeness. They 
extend throughout the greater part of the length of the 
abdominal cavity, the left being, however, longer than 
the right. Throughout their length they are divided 
into irregular lobes by transverse incisions and shal- 
lower constrictions. The length of the left testis (ts) is 
55 cm., its greatest breadth 7V g cm., and its greatest 
thickness 4 cm. The corresponding dimensions of the 
right testis (td) are respectively 49 cm., 6 cm., and 3 
cm. So oblique is the relative position of each testis to 
the other that the hind extremity of the left only ex- 
tends to a point distant 11 cm. from the anal aperture, 
a distance which in the case of the right testis is re- 
duced to 7 cm.“ Their outside (facing the wall of the 
abdominal cavity) is convex, their inside flatter; the 
former is covered with an extremely thin membrane, 
the latter with a thicker continuation of the mesorchium, 
the peritoneal membrane that holds each testis suspend- 
ed partly (in front) from the wall of the abdominal 
cavity, partly (further back) from the air-bladder, partly 
(behind the air-bladder, which terminates about 197 2 
cm. in front of the vent) from the kidneys. Posteriorly 
the mesorchium is thickened (* — **), on the left testis 
for a distance of about 10 cm., on the right for about 
8 cm. Behind this thickening the testes are free from 
their suspensory membrane, the left only for a, very 
little way, the right for a distance of 67 2 cm. On the 
inside, in front near the middle of the breadth or even 
near the lower, free margin of the testicle, behind 
near its upper (suspensory) margin, runs a wide ef- 
ferent duct (vas deferens ), the radices of which ramify 
in all parts of this side. The efferent duct is skirted 
by a sharp-edged, rather thin, adipose band, with free 
margin and in some places 1 cm. broad, at other 
points narrower or even merging into the mesorchium. 
Air blown into the efferent duct spreads partly into 
its ramifications, partly, in the hind portion of the 
testis, into large lacunae between the testicular mem- 
brane and the stroma. Mercury injected into the 
duct penetrates through canals in the thickened part 
(* — **) of the mesorchium into the kidneys. It is 
thus evident that the sperma may find egress in this 
direction and through the ureter; but another passage 
seems also to be afforded. Both male and female Stur- 
geon-fishes possess peritoneal funnels, not unlike those 
we have seen above in female Sal monoids, especially 
in the Smelt and Capelin. But here these funnels are 
developed into independent ducts (71/), distinct from 
the true organs of generation, densely ciliated, and 
opening behind into the ureter. They are thus fully 
homologous with the so-called Mullerian ducts (ovi- 
ducts) of the Ganoids, Lung-fishes, Selachians, and the 
higher vertebrates. In the males of most vertebrates 
they are more and more reduced, the testes being fur- 
nished instead with deferent canals through the pro- 
nephros; but in the Sturgeon-fishes this transformation 
has not advanced so far, the males having as large, 
as open, and apparently quite as functional Mullerian 
ducts as the females. In the above-mentioned male 
Sturgeon the inner (abdominal) aperture (apm) of the 
left Mullerian duct lies about 31 1 2 cm., that of the 
right 32 1 / 2 cm., in front of the anus; and the former 
duct measures 15 cm. to its posterior aperture, which 
opens into the ureter. Frequently*, at least in male 
and female Sturgeons not yet in spawning condition, 
the last-mentioned aperture is closed; but to judge 
by the perfect development of the Mullerian ducts in 
our specimen, it would seem quite probable that they 
may be functional in breeding fish of both sexes, even 
if the sperma of the males may also find its way into 
the ureter by another mode of passage. 
On each side of the anus the Sturgeon-fishes are 
commonly furnished with a. so-called abdominal pore c , 
an aperture b}^ means of which the abdominal cavity 
communicates with the surrounding water. It is often 
wanting, however, as in the specimen just described. 
Its function is somewhat doubtful, though probably 
a In another Sturgeon the relations were reversed; the left testis extended further, even in a backward direction, than the right. 
h Cf. Jungersen, Bidr. Kundsk. Konsorg. Udv., Disp. Kbhvn 1889, p. 101. 
c Cf. Weber, Morphol. .Tahrb., P>d XII (1886), p. 366. 
