122 EDWARD PHKLPS ALUS, JUN. 



from the arraugeineut found in LEemargiis in tliat tliei'e is 

 an anterior anastomosis^ indicated but not found in Ltemar- 

 gus, and that in this last fish the posterior, interuasal anasto- 

 mosis is formed by the juxtaposition and fusion of longitu- 

 dinal sections of the canals of opposite sides, as in Mustelus, 

 and not by the fusion, end to end, of transverse sections of 

 canals. Another difference between the two fishes is, that, 

 in Lasmargus, the anastomosis of the distal end of the supra- 

 orbital canal with the infra-orbital canal, lies at a point on this 

 latter canal, that is, morphologically, anterior to the one at 

 which the hyomandibular canal is given off, while in Raia 

 it lies morphologically posterior to that point. Mustelus here 

 agrees with Laemargus. 



In ChimaBra (11) the anterior, antorbital section of the 

 infra-orbital canal is probably the one that is innervated by 

 the anterior division of the outer buccal nerve of Cole's de- 

 scriptions. 



In Mustelus, posterior to the anterior section of the infra- 

 orbital canal above discussed, there are three principal groups 

 of infra-orbital organs, each of which is separated into two or 

 more, more or less distinct sub-groups. One of these three 

 principal groups is suborbital in position, and includes organs 

 46 to 78. The other two together are postorbital and otic in 

 position, and include organs 79 to 110. 



Organs 46 to 78, which form the first of these three groups, 

 are innervated by the first three branches that arise from the 

 buccalis beyond its ganglion. They arise consecutively from 

 the nerve, beginning at some little distance beyond its gan- 

 glion, and the third and more anterior branch is so large that 

 it may be called a division of the nerve rather than a branch 

 of it. The two posterior branches innervate, the one organs 

 70 to 74, and the other organs 75 to 78. The anterior branch, 

 or division, of the nerve breaks up into several smaller 

 branches and one large one, the smaller branches being 

 destined to supply organs 46 to 69, and the large one to 

 supply the buccal group of ampullas. 



Organs 79 to 86 form the second one of the three groups, 



