ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 695 



This pad of tissue commences about 50 sections in front of the posterior extremity of 

 the palato-ethmoidalis profundus, and its tapering non-cartilaginous dorsal portion 

 extends upwards from the mucosa like a wedge towards the subnasal bar, separating the 

 two profundus muscles in the median plane for about 25 sections. The pad does not 

 quite reach the subnasal bar, except where it bends upwards and backwards, and is 

 connected by fascia with its posterior extremity, as described in my first Part. The two 

 profundus muscles are closely opposed to the pad, but I do not think they are attached 

 to it, as stated in my first Part. 



P. Furbringer figures the present muscle as inserted into the entire length of the 

 cornual cartilage, and states further that some fibres are inserted into the palatine bar 

 itself. My dissections and sections agree with neither of these statements, but the 

 latter is probable enough, as the fibres extend right to the boundary between the two 

 cartilages in question. In Bdellostoma, according to J. Muller, the muscle has a 

 strongly pyramidal shape, the apex of the pyramid being inserted into the cornual 

 cartilage. In Myxine the insertion is, on the other hand, a very broad one, although 

 narrower than represented by P. Furbringer. 



The action of the profundus muscle, by approximating the two cornual cartilages, 

 and consequently the lateral labials, is to compress the mouth cavity laterally. 



10. M. quadrato-palatinus. (Fig. 11, q.p.) 



J. Muller, Anzieher des Schlundkorbes (p. 261). 



A moderately strong triangular-shaped muscle, with the apex directed forwards, and 

 covered by the palato-coronarius in front. Internally it abuts on the lateral roof and 

 dorso-lateral wall of the mouth. 



The quadrato-palatinus arises by a broad origin (forming the base of the triangle) from 

 the ventral margin and internal surface of the pterygo-quadrate from immediately behind 

 the transverse zone of soft cartilage separating it from the palatine up to the similar 

 zone of soft cartilage at about the middle of the inferior process of the pterygo-quadrate 

 (i.e. mostly from the anterior process of the latter). P. Furbringer gives the origin 

 from the lateral margin only, but both my dissections and sections support the state- 

 ment of the origin given above. In the sections on the left side the origin extended 

 back to the posterior extremity of the inferior process, and thus the muscle arose from 

 the entire length of the anterior and inferior processes, but on the right side it did not 

 go back so far, though further than described above. 



The fibres of the pterygo-quadrate pass forwards, strongly converging, and merge 

 into a long powerful tapering tendon which arises from the ventral surface of the 

 muscle and courses straight forwards (but slightly inwards) under the palato-coronarius 

 and opposed to the lateral roof of the mouth, to be inserted into the latero-ventral 

 surface of the anterior extremity of the palatine bar, i.e. just posterior to where it fuses 



