No. 2.] MORPHOLOGY OF THE MYXINOIDEI. 197 



consisting of nine longitudinal bars and two transverse con- 

 necting bars, an anterior and a posterior. 



Of the nine longitudinal bars, seven are dorsal and two 

 lateral. The seven dorsal bars are slender parallel rods, sepa- 

 rated by spaces wider than the width of a bar. These bars 

 support the roof of the olfactory capsule and correspond to 

 the seven folds of mucous membrane which hang from the 

 roof inside the olfactory capsule. The lateral bars are two 

 somewhat irregular flattened cartilaginous plates which support 

 the lateral walls of the olfactory capsule. The exact shape of 

 these cartilages, which we shall call the lateral plates, varies in 

 different specimens. Anteriorly a process is given off from 

 the inferior angle, which runs forward and connects with the 

 end of the last nasal arch. The anterior superior angle of the 

 plate is connected with the end of the anterior connecting bar. 

 The anterior portion of the lateral plate extends in a longitudi- 

 nal direction. Posteriorly, however, the plate curves around, 

 extending downward and inward toward the median line under 

 the olfactory capsule. The posterior ends of the two plates 

 do not fuse, but end in the inferior wall of the capsule near 

 each other. A short distance from the posterior ends of the 

 lateral plate a slender process is given off posteriorly, which is 

 closely connected with the corresponding trabecula near the 

 point of attachment to the palatine bar. A case of actual 

 fusion between the lateral plate process and the trabecula has 

 not been observed, however. 



The posterior connecting bar is a narrow strip placed trans- 

 versely across the roof of the olfactory capsule. It connects 

 the posterior extremities of the nine longitudinal bars. The 

 anterior connecting bar is a similar band, transversely placed, 

 and giving attachment posteriorly to the anterior ends of the 

 nine longitudinal bars. Anteriorly the anterior connecting 

 bar gives off three processes which connect it with the last 

 nasal arch. Thus, by means of these three connecting processes, 

 together with the anterior processes from the lateral plates, 

 the space between the last nasal arch and the anterior mar- 

 gin of the olfactory capsule is divided into four parts — two 

 dorsal, somewhat elliptical, and two lateral, nearly circular. 



