274 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



V. CERATOMYXA Thdlohau, 1892. 



EtymolngjT not given. 



Bull. Soc. philoinat. Paris, iv, pp. 1G9, 171, 175; ib., Gurley, 1893, Bull. U. S. 

 Fish Com. for 1891, xi, pp. 411-12, 420; ih., Brauu, 1893, Centialbl. f. 

 Bakt. u. Parasitenkde, xiv, pp. 738-9; ib., Brauu, 1894, Ceutralbl. f. Bakt. 

 u. Parasiteukde, XV, p. 87. 



Befinition. — Chloromyxidoe with bilaterally symmetrical, trau.sversely 

 exteuded, siibisosceles-triaiigular si)oics wiiose breadth yreatly exceeds 

 the length; valves hollow-conical with solid tips; sporoplasm uuilater- 

 ally and asymmetrically situated; typ3, C. sphcvrulosa. 



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 iuter- 

 capsular; (2) spore laterally extended; (3) valves bilaterally subsym- 

 mctrical; (4) decided sporojjlasmic bilateral asymmetry. 



On the other hand the supposition that this plane corresponds to the 

 longitudinal necessitates the following snpi)o&itions: (1) That the ver- 

 tical plane cun he perca2)siilar; (2) that the spore is vertically extended; 

 (3) valves superior and iuferiorly 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 i)lane can be per capsular., ^ 

 and [h) 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 [j\[yxoholns nnica2)snlatus, ilL ineqnalis, M. strongyUirus). 



Two other characters should be noted. As in the other forms hab- 

 itant in the tiuid-filled organs, the Ceratomyxa species are never seen 

 "encysted." Further, 3 out of the 4 known species possess the strik- 

 ing peculiarity of hisporogenesis, each myxosporidium producing only 

 2 spores. The fourth species presumably (from Th^lohan'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 mcr- 

 lucii, a gall-bladder species provisionally and doubtfully referred to 

 Myxoholus (see p. 242). 



Finally, while this paper was passing through the press, M. Th61ohan'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 ])lane, -which -would thus be x)ercap8ular). Tho only species in which 

 by any possibility the vertical piano could be asserted to be pen'ajjsular is Ci/s^o- 

 discus? di2)lojys, but here the couditioTi is at least eciually we^l (and I think much 

 better) explained on tiio view that the iiiti'rc(q}.iii}ar i)lano is the vertical. 



"Compt. Rend. Acad. Sci. Paris, 1894, cxviii, pp. 428-430. 



