No. 2.] MORPHOLOGY OF THE MYXINOIDEI. 2OI 



rods, lying in the same horizontal plane, but curved so as to 

 be convex outward. They are closest together posteriorly, 

 where they are attached on each side of the palatine commis- 

 sure {cm). Anteriorly they diverge laterally and curve around 

 so that the most anterior portions run parallel and end in a 

 slender tip on each side of the nasal tube, a short distance 

 behind its anterior end. The anterior ends of the cornual 

 cartilages are connected by ligaments with the lateral labial 

 cartilages at the base of the first tentacular cartilage. 



In the median line between the cornual cartilages, and 

 directly under the floor of the anterior portion of the nasal 

 tube, is the unpaired stibnasal cartilage (PI. XXII, Fig. 6 ; 

 PI. XXIII, Fig. 7, N). This is a rather strong, fusiform rod, 

 thickest in the middle portion, somewhat nearer to the anterior 

 end, and tapering anteriorly and posteriorly. Near the poste- 

 rior end it becomes flattened and at the extremity expands lat- 

 erally into two small processes. The posterior end is attached 

 to the dorsal side of the palatine commissure, just in front of 

 its posterior margin. Anteriorly it attaches in the median line 

 to the transverse labial cartilage. 



The labial cartilages (PI. XXII, Figs. 5, 6; PI. XXIII, 

 Fig. 7) support the oral margin dorsally and laterally, and give 

 attachment to the tentacular cartilages. The transverse labial 

 cartilage is an unpaired transverse bar lying in the dorsal por- 

 tion of the oral margin. The lateral halves meet at an angle 

 in the median line, so that the bar may be described as an arch, 

 concave forward. Laterally the ends of the bar are directly 

 continued into the second pair of tentacular cartilages (4). 

 These extend outward and forward, tapering gradually to a 

 point. In the median line, posteriorly, the transverse labial 

 cartilage is attached to the anterior end of the subnasal carti- 

 lage, as already mentioned. 



i:\i& lateral labial cartilages (PI. XXII, Figs. 5, 6 ; PI. XXIII, 

 Fig. 7, Lc) are a pair of somewhat slender cartilaginous rods 

 lying in the lateral margin of the mouth, surrounded by mus- 

 cles, and supporting the first and third pairs of tentacular car- 

 tilages. Posteriorly they are attached to the antero-external 

 angles of the basal plate. From this point they curve forward, 



