THE INFRA-ORBITAL TRUNK. I9I 



is not probable that there is any considerable number of 

 superficial sense organs in this region other than those 

 figured, for the surface preparations failed to demonstrate 

 them, while those found were in about the same positions 

 as figured. 



The morphology of the three organs which, together 

 with the three of the opposite side, form the supra-maxil- 

 lary commissure is, I think, quite clear. They and their 

 nerve evidently belong to the lateralis system. In 

 Lophius (Guitel, '91) there is a commissure of the lateral 

 lines in the corresponding position and with the same in- 

 nervation (see my Fig. 6). In Amiurus and Silurus there 

 is a similar line of pit-organs (Allis, '97, p. 629). The 

 three organs about the nasal apertures {a. b. c.) and the 

 three similar ones innervated from the superficial ophthal- 

 mic nerve (^. //. t.) offer much greater difficulties. The 

 nerves supplying them are smaller than those which 

 supply the commissural organs last mentioned, but larger 

 and more heavily medullated than typical communis 

 fibres so that the nerve supply here is ambiguous, as 

 either communis or lateralis fibres might be drawn off for 

 them. I rank them provisionally with the pit-line and 

 other accessory lateral line organs, and suggest that the 

 buccal group may be related to the inner buccal group of 

 ampullae of selachians. Comparative or embryological 

 studies might, however, relegate them to the terminal bud 

 system. 



Cole ('98a, p. 158, foot note) describes an essentially 

 similar nerve in Gadus from the r. buccalis to supply pit- 

 organs in front of the nasal appertures and near the 

 cephalic end of the supra-orbital canal. He adds: "This 

 curious nerve is not represented in other fishes, and 

 probably consists of lateral superficial ophthalmic fibres 

 following a buccal course." From the quotations given 



