694 MR FRANK J. COLE 



According to P. Furbringer, the palato-ethmoidalis superficialis produces a dorsal 

 flexion of the subnasal bar and a retraction of the dorsal margin of the mouth, in order 

 to bring the median tooth into a favourable position for piercing the prey. 



9. M. palato-ethmoidalis profundus. (Figs. 3, 10, 11, p. e. p.) 



J. MtJLLEB, Pyramidale MusTcel der Schnautze (p. 259). Compressor der Mundhbhh (p. 332). 



Lies largely under the palato-ethmoidalis superficialis. It is a short but powerful 

 muscle, and appears on the roof of the mouth (covered, of course, by the mucosa), as 

 shown in fig. 10. Of this muscle Allis says # : "This latter muscle I find, however, 

 in B. dombeyi as two wholly separate muscles, one lying dorsal to the other, and the 

 two crossing each other at an angle. Both muscles extend from the nasal bar to the 

 cornual cartilage, and they both must act as adductors of that cartilage, drawing it 

 toward the nasal bar." There are certainly clear indications anteriorly of the division 

 mentioned by Allis (cp. fig. 11), but behind, the two parts of the muscle are generally 

 not separable. In front, however, the anterior, inner or ventral, division passes obliquely 

 backwards, and the posterior, outer or dorsal, division obliquely forward. Hence, as 

 Allis states, the fibres cross at an angle. In one specimen I found the two divisions 

 entirely distinct, as in B. dombeyi. It is not easy to study this condition in transverse 

 sections, but in a series of vertical longitudinal sections I found the muscle consisting 

 of a thin postero-dorsal portion and a more extensive and greatly thicker ventral 

 portion, the distinction being observable throughout the entire extent of the muscle. 

 I believe, however, it is only another expression of the tendency noticeable in many of 

 the muscles of Myxinoids for the fibres to collect into large separate divisions, which 

 might almost be described as separate muscles. Compare, for example, the velo- 

 quadratus muscle, where there are three of these divisions. 



The palato-ethmoidalis profundus arises from the lateral (in front, ventro-lateral) and 

 ventral surfaces of about the posterior two-thirds of the subnasal bar. P. Furbringer 

 says the posterior half, and J. Muller the whole in Bdellostoma. In the sections it 

 works out as the posterior two-thirds exactly. The fibres of the muscle pass outwards 

 and somewhat downwards, and converge from both extremities to be inserted into the 

 dorso-internal surfaces (median margin — P. Furbringer) of slightly more than the 

 posterior two-thirds of the cornual cartilage opposite the "origin" of the copulo- 

 palatinus. In the sections the insertion had precisely the same extent. 



Since the area of origin is greater than that of the insertion, both as regards vertical 

 surface and longitudinal extent (in the latter respect extending over 172 sections as 

 against 98), it follows that all the fibres arising from the subnasal bar cannot be 

 inserted into the cornual cartilage. Posteriorly a large number of them are 

 inserted into the ventral fascia of the muscle extending transversely from the cornual 

 cartilage to the median pad of soft pseudo-cartilage described on p. 765 of my first Part. 



* Op. cit., p. 272. 



