104 RDWARD PHKLPS ALUS, J[TN. 



Supra-orbital Canal. 



The siipra-oibital canal begins near the lateral edge of the 

 ventral surface of the head, postero-lateral to the nasal 

 aperture, and slightly anterior to the transverse plane of 

 the anterior edge of the mouth cavity. At this morpho- 

 logically anterior, or distal, end of the canjil it is in direct 

 communication with the infra-orbital canal in the region 

 opposite organs 45 to 50 of that line. As the infra-orbital 

 organs including and anterior to organ 45 form a group 

 separate and distinct, in their innervation, from the organs 

 including and following organ 4G, it is probable that the 

 anastomosis of the two canals takes place between organs 

 45 and 46. 



Starting from this point the supra-orbital canal runs for- 

 ward and mesially in a gentle curve, parallel to the lateral 

 edge of the head, and, near the most anterior point of its 

 course, meets and anastomoses with the anterior end of the 

 infra-orbital canal, the two canals meeting, at approximately 

 a right angle, between organs 34 and 35 supra-orbital. 



Anterior to this point the supra-orbital canal runs forward, 

 or forward and laterally, for a very short distance, and 

 reaches the edge of the snout, where it turns upward and 

 reaches the lateral surface of the head. There it at first runs 

 upward, backward, and laterally, in a nearly straight line, 

 until it reaches a point somewhat anterior to the anterior edge 

 of the eye. There it turns forward mesially and upward in 

 a short curve, continues in that direction for a short distance, 

 and then turns upward and backward in a second short curve, 

 beyond which it runs backward, dorso-mesial to the eye, in 

 a line approximately parallel to the mid-dorsal line of the 

 head. Dorso-mesial to the hind edge of the eye it anasto- 

 moses by its hind end with the infra-orbital canal between 

 organs 102 and 103 of that line, that is, between the otic and 

 postfrontal groups of infra-orbital organs. 



The canal at its distal end lies ventro-lateral to the hind 



