274 EEPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



V. CERATOMYXA Th<3lobau, 1892. 



Etymology not given. 



Bull. Soc. philomat. Paris, iv, pp. 169, 171, 175; ii., Gnrley, 1893, Bull. U. S. 

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

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

 u. Parasitenkde, XV, p. 87. 



Definition. — Chloroinyxidce with bilaterally symmetrical, transversely 

 extended, subisosceles-triangular spores wiiosebreadth greatly exceeds 

 tlie lengtli; valves lioUow-conical with solid tips; sporoplasm imilater- 

 ally and asymmetrically situated; typ?, C. splum-ulosa. 



The i^osition 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 Avhether the plane of junction of the valves is the vertical or the 

 longitudinal. If it be vertical, we then have: (1) Yertical plane inter- 

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

 mctrical; (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 ciinhe j^ercapsnlar; (2) that the spore is vertically extended; 

 (3) valves superior ajid inferiorly subsymmetrical; (4) decided (sporo- 

 plasmic) snpero inferior asymmetry. 



While admitting the striking anomaly exLibited 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 percapsxdar^ ^ 

 and (b) that the spore is greatly extended supero-iuferiorly, of neither of 

 which conditions any other known species exhibits an example. There 

 are, however, species whicli exhibit, though in a less degree, bilateral 

 asymmetry [Myxoholus uniccqysulatus, M. inequalis, M. strongylurus). 



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

 itant in the fluid-tilled 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 Thelohan'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- 

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

 Myxoholus (see p. 242). 



Finally, while this paper waspassingthrough the press, M. Thelohan's 

 recent paper ^ was seen. It seems to imply very strongly two things, 



'No known iustnnce exists of 2 capsules beiug 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 plaue could be asserted to be percapsular is Ci/sto- 

 disciis? diploxys, but here the condition is at least equally weM (and I think much 

 better) explained on the view that the intcrcapsiday plane is the vertical. 



2Compt. Rend. Acad. Sci. Paris, 1894, cxviii, pp. 428-430. 



