1906.] NERVES OF CHLAMYDOSELAC'HUS ANGUIXEL'S. 961 



of the eye, the canal bends outward towards the nostiil, then 

 curves upward and forward almost to the end of the snout, where 

 it suddenly turns bac]i;ward, passes above the nostril, and finally 

 bends venti^ad to join the Infi-a-orbital canal at D. In the supra- 

 orbital canal of one specimen there were 55 neuromasts and 

 openings on one side and 49 on the other. A second specimen 

 had 41 on one side and 40 on the other. The sense-organs, as 

 judged by the point of entrance of the nerve, are usually opjDosite 

 the canal-ojDenings in the supra-orbital as well as in the other 

 canals. The openings may be at the end of short tubules, or on 

 the canal itself. The longest tubules on this canal are less than 

 5 mm. in length, and these are found near the point of union 

 with the Infra-orbital canal. Thi'oughout the head-canals the 

 neuromasts are placed at approximately regular distances (5 mm.) 

 a.part. According to Garman's figure (10. pi. xvii.) there is a 

 canal uniting the anterior end of the Infra-orbital canal with the 

 most anterior point of the supra-orbital canal. This additional 

 canal is called by Garman, the prenasal canal. It was not present 

 in the specimens dissected by me, and there was no trace of its 

 openings in the sj^ecimens examined externally. From Garman's 

 description it is not possible to determine whether the prenasiil 

 canal joins the infra-orbital. In Garman's figure (10. pi. xvii.) 

 the supra-orbital (rostral and subi'ostral canals) curves forward 

 much higher up the snout than in the specimens examined, in 

 which case an additional canal would jirobably extend on to the 

 snout. But it is imjjrobable that this canal would join with the 

 infra-oi-bital. 



The Infra-orhital canal (A, B, E, D, F), which includes the 

 occipital, orbital, orbito-nasal, and nasal canals of Garman, in- 

 nervated by the buccalis and otic branches of the Facialis, begins 

 at A as a direct continuation of the main lateral canal. It gives 

 oflT the supra-orbital canal, and then passes downwards behind 

 the eye. This portion is curved, the first third being directed 

 forward and the remainder backward. The backward curve was 

 probably produced by the lengthening of the jaws. At a point 

 above the mouth (E), but not as caudad as the angle, the canal 

 bends sharply forwards and runs along the upper jaw under the 

 nostril to terminate at the median line, close to its fellow of the 

 opposite side, from which it is separated only by a thin wall. In 

 one specimen this canal had 52 neuromasts and openings on one 

 side, and 50 on the other. In a second specimen the numbers were 

 47 and 46 respectively. The longest tubules in Chlamydoselachus 

 occur on this canal, in the first part of its post-orbital ventral 

 course. Here a few tubules reach a length of 1 cm. 



The Hyomandihular canal (E, G, J, L, K, I), which includes 

 the angular, jugulai-, spiracular, oral, and gular canals of Gar- 

 man (10), innervated by the external mandibular branch of the 

 Facialis, is the most extensive and complicated part of the canal 

 system. It branches out from the infra-oi-bital canal to run back- 

 wards above and beyond the mouth, with a somewhat tortuous 



