ON THE GENERAL MORPHOLOGY OF THE MYXINOLD FISHES. 689 



posterior region were inserted into the first ring of the nasal tube in front of the 

 ethmoideo-nasalis, and from thence passed obliquely backwards, outwards, and downwards 

 under that muscle, as shown in the figure. I have not, however, seen this since. Some 

 of the fibres arise (? insertion) from the so-called transverse labial cartilage (see Part I. 

 p. 770) and also from the anterior extremity of the subnasal bar immediately below and 

 in front of the origin of the tentaculo-ethmoidalis. but most of them arise from the stout 

 ventro-lateral superficial fascia near the anterior extremity of the snout, course more or 

 less transversely on to the adjacent dorso-lateral surface of the same side (cp. fig. 10), 

 and are inserted (? origin) in front of the middle third of the internal portion of the 

 third tentacular cartilage into the antero-internal fascia of the anterior portion of the 

 head of the copulo-tentaculo-coronarius from the third tentacle. 



Anterior Region. — More definitely transverse than the posterior region, and situated, 

 in a lateral view, apparently anterior to it, and between it and the anterior division of 

 the copulo-tentaculo-coronarius. Most of its fibres course direct from the tough 

 ventro-lateral to the dorso-lateral fascia of the same side, and this region is reinforced 

 by fibres from the first tentacle. Ventrally there is a distinct transverse commissure 

 in front of and ventral to the anterior extremity of the subnasal bar, and seen after 

 removal of the skin, the fibres of which arise partly from the bases of the second 

 tentacles and partly from the an tero- ventral fascia of the anterior region of the present 

 muscle ( = ventral commissure below — cp. fig. 10). All the fibres from the second 

 tentacle, however, do not pass over into the commissure, but some of them pass on to 

 the transverse labial cartilage and the anterior extremity of the subnasal bar ( = dorsal 

 pseudo-commissure below). 



In the sections, the transversus oris arises (? insertion) by a pointed posterior 

 extremity from the internal surface of the sheath of the third tentacular cartilage just 

 within the contour of the body, and between the anterior division of the copulo- 

 tentaculo-coronarius (below) and the posterior division of the same (above). The latter, 

 however, soon dies away ; and as it does so, the transversus oris is attached to its internal 

 fascia and a number of fibres arise from this. The muscle has thus a double origin. 

 It now courses forwards as a clearly defined muscle lying immediately above the 

 anterior division of the copulo-tentaculo-coronarius, and external to, but somewhat below, 

 the tentaculo-ethmoidalis. The first change noticeable is that the ventro-external fibres 

 pursue a (very short) course of their own, and pass straight from the latero-external to 

 the ventro-external fascia — thus giving rise in dissection to an appearance as if the 

 muscle consisted of two divisions. The anterior division of the copulo-tentaculo- 

 coronarius lies in a depression on the outer surface of this portion of the muscle. As 

 the transversus oris passes forwards its fibres converge somewhat, and it now lies almost 

 directly between the two muscles mentioned above, the latter being respectively 

 external and internal to it (cp. fig. 10). Not much of it now appears on the lateral 

 surface of the snout, and still less on the ventral surface. In front of this, however, it 



