106 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
ORGANAL DISTRIBUTION. 
ORGANAL DISTRIBUTION OF THE GENERA AND SPECIES. 
Perugia! remarks that there is a marked difference in seat between 
the Myxosporidia of marine and those of fresh-water fishes. In marine 
fishes they occur principally in the gall bladder, while in fresh-water 
fishes their organal range is much wider. The finding of cysts on the 
branchie of the marine genus Mugil (see p. 213) rather corroborates 
than contradicts this view, inasmuch as these fishes ascend rivers for 
a long distance, and those which yielded the myxosporidian cysts also 
yielded a Trematode of a genus peculiar to fresh-water fishes, viz, Tetra- 
onchus vanbenedenti Par. & Per. 
The organal distribution of the Myxosporidia is very extended. The 
following points are of special interest, and comprise the principal 
anomalies of distribution not covered by the tables below. 
Nervous system.—No species have ever been reported. 
Testicle-—No species have ever been reported, a fact which,” consid- 
ering their frequency in the ovary, is very surprising (cf. the presence 
of “ Myxosporidium” bryozoides on the spermatoblasts of Alcyonella 
Jungosa; see p. 187). 
Superficial tract—General similarity of conditions, histologic struc- 
ture, and fauna justify the fusion of the general surface, skin, scales, 
the branchiz, the eye, and the air bladder into one tract. ‘The charac- 
teristics of this tract are principally the predominance of connective 
tissue, and (?) a relatively larger supply of oxygen (see p. 224). 
Air bladder: Only two species are known from this seat. Both of 
these occur in Cyprinide, in which the bladder communicates freely 
with the intestine, and hence presumably contains oxygen. This fact, 
the histologic similarity, and the fauna suggest very strongly the pro- 
priety of including the air bladder in the external tract. The species 
are Gen. incert. sp. 15 and Myzxobolus ellipsoides. 
Intestinal canal.—They would appear to be very rarehere. I am not 
aware that any species has ever been reported from the lumen, the 
nearest approach to it being one (Myxidium? sp. 102) from the bile- 
ducts. And yet such a species as the last must almost certainly find 
its way into the intestine; probably, however, as separated, single 
Spores, very difficult to find. In addition, Myxobolus ellipsoides and 
M. sp. 51 (the latter from the wall), and finally Gen. incert. sp. 17 
(which, however, may or may not be myxosporidian) occur on, or in the 
intestine? 
1Boll. Scientif., Pavia, 1890, x11, p. 139. 
°As remarked by Thélohan (Annal. de Microgr., 1890, 11, p. 197). 
3The fact that M. ellipsoides and M. sp. 51 are, of all the Myxosporidia, the species 
having the widest organal distribution, should not be lost sight of in considering 
their presence in unusual seats, 
