ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 693 



8. M. palato-ethmoidalis super jicialis. (Fig. 3, p. e. s.) 



J. Mulleb, Zuriickzieher der knochernen Stiitze der Schnautze (p. 258). Zuriickzieher der 

 Schnautzenstutze (p. 322). 



Superficially a powerful fan-shaped longitudinal muscle, with the handle directed 

 forwards. It is roughly triangular in transverse section, the outer or superficial area 

 representing the base of the triangle, with the apex directed inwards towards the subnasal 

 and palatine bars. In the sections, about the middle third of the muscle was divided into 

 two distinct portions — a dorso-horizontal plate-like portion and a ventral much larger 

 portion. It is covered largely by the tentacularis posterior, but its dorso-external 

 margin may appear on the surface between the latter muscle and the nasalis. 



The palato-ethmoidalis superficialis has a very broad origin, as follows : — (a) from 

 the lateral wall of the nasal capsule. As shown in fig. 3, this part of the origin extended 

 back under the eye for a short distance on to the cranium. In the sections it passed 

 back over, but not behind, the eye on the left side, but on the right side it terminated 

 in front of the eye ; (b) from the external fascia of the dorso-anterior border of the 

 copulo-quadratus profundus ; (c) from the dorso-external fascia of the palato- 

 coronarius ; (d) from the posterior third of the cornual cartilage (in a dissection). 

 Except perhaps for a very few fibres from the root of the cornual cartilage, this was 

 certainly not the case in the sections, the present muscle being excluded from the 

 cartilage by the insertion of the palato-ethmoidalis profundus ; (e) from the external 

 margin of the anterior half of the palatine bar (dissection). In the sections this part of 

 the origin is from the anterior three-fourths. Posteriorly, where the muscle fibres 

 themselves do not reach the bar, the internal apex of the muscle is connected with it by 

 a short strong ligament. The more superficial fibres are represented by a and b above, 

 and the deeper fibres by c, d, and e, these latter being the deepest and constituting the 

 apex of the triangle. 



In Bdellostoma, according to J. Muller, the palato-ethmoidalis superficialis arises 

 from the palatine bar only, whilst in Myxine P. Furbringer states that it arises from 

 the posterior half of the bar and from the " lateral region of the skull." 



The fibres of the palato-ethmoidalis superficialis pass forwards, rapidly converging, 

 and were inserted, in a dissection, into about the anterior third of the subnasal bar. 

 P. Furbringer says the middle third. In the sections the insertion covered exactly one- 

 half of the extreme length of the bar, i.e. it extended through 130 sections, whilst the bar 

 itself passed through 65 sections in front of and 65 behind it. Posteriorly, the muscle 

 is inserted into about the dorsal half of the lateral surface of the bar, the ventral half 

 being occupied by the origin of the palato-ethmoidalis profundus. As, however, the 

 latter muscle dies away, the superficialis extends over the whole of the lateral surface 

 of the bar, but at its anterior extremity it is again excluded from the lower part of the 

 lateral surface by the commencement of the insertion of the copulo-ethmoidalis. 



