k 



The Latero-Sensory Canals and Related Bones in Fishes. 445 



the lateral occipital. It then enters and traverses, in succession, the 

 superior and inferior "Scapulae" of Erdl's descriptions, those two 

 bones being', respectively, the suprascapular and supraclavicular. Be- 

 tween the points where the canal enters the anterior edge of the 

 squamosal and the anterior edge of the suprascapular, it lies along 

 the ventral margin of the "äussere Gehöröffnung" of Erdl's descriptions, 

 immediately internal to the ventral border of the so-called "Gehör- 

 deckel". And about midway between the dorsal end of the preoper- 

 cular canal and the anteiior edge of the suprascapular it gives off 

 the supratemporal canal. 



Four primary tubes, and but four, were found in the full length 

 of the main infraorbital canal. The anterior one of these tubes arises 

 from the canal near the hind end of the third from the last oi'bital 

 bone, or between that bone and the second from the last. It is a 

 relatively long tube, directed backward along the outer surface of the 

 muscles of the cheek. The second tube arises from the canal slightly 

 posterior to the point of anastomosis with the supraorbital canal, and is 

 undoubtedly the double tube formed where these two canals anastomose. 

 It runs backward immediately superficial to the main canal, and ex- 

 tends to the level of the dorsal end of the preopercular canal. No 

 tube was found where this latter canal anastomoses with the main 

 infraorbital. The third tube of the latter canal arises from it just 

 before it enters the suprascapular, and the fourth tube as it passes 

 from the latter bone into the supraclavicular. These two latter tubes 

 are short ones, the one directed downward and backward, and the 

 other upward and backward. 



There were in the full length of the main infraorbital canal, in 

 the specimen used for illustration, thirteen sense organs. The most 

 anterior one of these organs lies in that section of the canal that 

 lies in the groove on the lateral edge of the Nasenmuschel, the next 

 seven organs Ijdng, one in each one of the seven bones of the so- 

 called orbital series. The so-called Nasenmuschel is thus simply the 

 most anterior one of what is usually described as the infraorbital 

 chain of bones; and the most posterior so-called orbital bone is the 

 dermal postfrontal. Posterior to this latter bone the next two organs 



