394 H. B. POLLARD, 



Continuing forwards and downwards, through the adductor mandi- 

 bulae muscle, the Ramus mandibularis divides into R. R. mandibulares 

 externus {R. md. ext.) and internus. The R. mandibularis externus 

 lies outside the muscle and gives off a small branch, which runs 

 downwards and backwards to the skin outside the iMeckelian cartilage, 

 thence, passing outside the anterior portion of the Meckelian cartilage, 

 it continues forwards internal to the maxillary and coronoid tentacles, 

 and reaching the mental tentacle, it divides into three small twigs 

 which supply the anterior face of this tentacle, the skin there being 

 remarkably rich in sense organs. 



The Ramus mandibularis internus divides above the Meckelian 

 cartilage into R. submandibularis (R. suhm.) and R. mentaMs {R. ment.). 

 The former turns down outside the mentomeckelian process, while the 

 R. mentalis continues on above it and passing forward horizontally, 

 parallel to the R. mandibularis externus , divides into small twigs 

 which supply the posterior face of the mental tentacle. 



An Ophthalmicus profundus is only represented by certain fibres 

 running in the course of the Ramus ophth. superficialis of the Facial. 



Sensory Tentacular Nerves of Myxine (Fig. 11), 



For purposes of comparison and in view of the object of this 

 paper, I venture to give a figure of the terminal distribution of the 

 sensory branches of the Trigeminus in Myxine., with some description, 

 though I have only one point to add to the almost perfect account 

 given by Johannes Müller in his classical memoir. 



In the figure the anterior part of the irregular nasal skeleton is 

 shown, and supplying the skin in this region are several twigs be- 

 longing to one of the branches of the Ophthalmicus profundus {R.o.p.)., 

 the upper terminal branch of the first branch of the Trigeminus of 

 Müller, 5'" in his figures. One twig also proceeds to the premaxil- 

 lary tentacle (shown in my figure with an asterisk). 



The branch termed Ramus premaxillaris (R.pmx. in the figure) 

 is Müller's ''lower stouter branch of the first branch of the Trige- 

 minus, 5"" ". It runs alongside the premaxillary i)iece, the "vordere 

 knöcherne Stütze der Schnauze", and, after giving off motor branches, 

 supplies the first or premaxillary tentacle. 



The above two branches form the "upper anterior branch of the 

 Trigeminus" and both are said to run above the optic nerve in 

 Bdellostoma. They are by most authors termed ophthalmic branches, 

 and I have kept that name in my preliminary communication. 



