ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 699 



The subsequent course of the anterior division is best dissected in specimens that have 

 been preserved in an acid medium, such as Perenyi's fluid. It passes forwards and 

 upwards as a compact bundle in a gentle curve at the lateral margin of the mouth, 

 and is finally inserted into the ventro-external surface of the root of the second 

 tentacular cartilage, or what is called by Ayers und Jackson the transverse labial 

 cartilage. 



The copulo-tentaculo-coronarius has obviously a complex function, which, can only 

 be ascertained by direct experiment. It will, however, at least retract the lateral 

 labial and the second, third, and fourth tentacles. In Bdellostoma, according to 

 \ J. Muller, the head from the fourth tentacular cartilage is wanting, and the origin of 

 the first or principal head is from the internal bar of the anterior segment of the basal 

 plate. 



13. M. coronarius, F.J.C. (Figs. 3, 11, co.) 



P. Furbringer, " Endinsertion " of the copulo-tentaculo-coronarius (p. 17). 



According to P. Furbringer this muscle represents the final insertion of the copulo- 

 tentaculo-coronarius, but as I find no connection between these two muscles beyond 

 that which commonly obtains between adjacent muscles, I have separated it under the 

 above name. Its fibres are quite independent, and if we are to regard, for example, the 

 palato-ethmoidalis profundus as a separate muscle from the copulo-palatinus, we cannot 

 describe the present muscle as simply the insertion of another. Its position and 

 relations are also against this. 



The coronarius is a very small muscle, with a somewhat curious anatomy. It arises 

 from the dorsal surface of the lateral labial cartilage, just behind where the latter fuses 

 with the cartilage of the third tentacle. The origin lies immediately in front of and in 

 contact with the ligamento-cartilaginous connection between the lateral labial and 

 cornual cartilages described on pp. 765-6 of my first Part, and shown (but not lettered) 

 in fig. 2. Cp. also fig. 1 1 of present Part. This connection, by the way, I now believe 

 to be constant. 



At its posterior extremity in the sections, and in one dissection, the coronarius 

 extended downwards from its dorsal position on the lateral labial over the external 

 surface of this cartilage, and at the same time the insertion of the posterior division 

 of the copulo-tentaculo-coronarius rose upwards from its ventral position on the same, 

 also over its external surface, to meet it. A careful examination of both sides of two 

 series of sections differently stained has, however, convinced me that the latter fibres 

 are only inserted into the external fascia of the coronarius, and that the fibres of the 

 two muscles are quite independent. Further, in two dissections, the muscles were 

 obviously distinct, and almost at right angles to each other. And even if the fibres of 

 the two were here continuous, only a small portion of the coronarius would be accounted 

 for, and by far the major portion would have an origin of its own from the lateral 

 TRANS. ROY. SOC. EDIN., VOL. XLV. PART III. (NO. 26). 100 



