274 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES, 
V. CERATOMYXA Thélohan, 1892. 
Etymology not given. ' 
Bull. Soc. philomat. Paris, 1v, pp. 169, 171, 175; ib., Gurley, 1893, Bull. U.S. 
Fish Com. for 1891, x1, pp. 411-12, 420; ib., Braun, 1893, Centralbl. f. 
Bakt. u. Parasitenkde, xIv, pp.738-9; ib., Braun, 1894, Centralbl. f. Bakt. 
u. Parasitenkde, xv, p. 87. ; 
Definition.—Chloromyxide with bilaterally symmetrical, transversely 
extended, subisosceles-triangular spores whose breadth greatly exceeds 
the length; valves hollow-conical with solid tips; sporoplasm unilater- 
ally and asymmetrically situated; typ, C. spherulosa. 
The position of this genus in the system depends upon the interpre- 
tation of its symmetry. Admitting (as we may safely do) that the 
position of the capsules marks the anterior extremity, the question 
arises whether the plane of junction of the valves is the vertical or the 
longitudinal. If it be vertical, we then have: (1) Vertical plane inter- 
capsular; (2) spore latérally extended; (3) valves bilaterally subsym- 
metrical; (4) decided sporoplasmic bilateral asymmetry. 
On the other hand the supposition that this plane corresponds to the 
longitudinal necessitates the following suppositions: (1) That the ver- 
tical plane can be percapsular; (2) that the spore is vertically extended; 
(3) valves superior and inferiorly subsymmetrical; (4) decided (sporo- 
plasmic) supero-inferior asymmetry. 
While admitting the striking anomaly exhibited by this species in 
its bilaterally asymmetric distribution of the sporoplasm (which cer- 
tainly warrants its generic separation), it seems more easy to accept 
this than to admit (a) that the longitudinal plane can be percapsular, ' 
and (b) that the spore is greatly extended supero-inferiorly, of neither of | 
which conditions any other known species exhibits an example. There 
are, however, species which exhibit, though in a less degree, bilateral 
asymmetry (Myxobolus unicapsulatus, M. inequalis, M. strongylurus). 
Two other characters should be noted. As in the other forms hab- 
itant in the fluid-filled organs, the Ceratomyxa species are never seen 
“encysted.” Further, 3 out of the 4 known species possess the strik- 
ing peculiarity of bisporogenesis, each myxosporidium producing only 
2 spores. The fourth species presumably (from Thélohan’s silence) does 
not possess this character. It is well to note that this character is 
possessed by only one other species, viz: Perugia’s Myxosporidium mer- 
lucit, a gall-bladder species provisionally and doubtfully referred to 
Myzxobolus (see p. 242). 
Finally, while this paper was passing through the press, M. Thélohan’s 
recent paper”? was seen. It seems to imply very strongly two things, 
‘No known instance exists of 2 capsules being placed one above the other (i. e., 
in the vertical plane, which would thus be percapsular). The only species in which 
by any possibility the vertical plane could be asserted to be percapsular is Cysto- 
discus? diploxys, but here the condition is at least equally we'l (and I think much 
better) explained on the view that the intercapsular plane is the vertical. 
2Compt. Rend. Acad. Sci. Paris, 1894, cx vu, pp. 428-430. 
