THE CRANIAL NERVES AND LATERAL SENSE ORGANS OF EISHES. 119 



" Oadus carbonarius'' {=G. vlrens) (pi. v.) and " Gadus lota" (pi. vi.), and his work 

 is remarkably accurate for the time it was published, anf'^ must certainly be regarded as 

 a pioneer research. Cunningham (1890, 55) says (p. 77) : "In the Cod, which may be 

 taken as exhibiting pretty nearly tlie original condition of the cephalic tubes of the Sole 

 and other tlat flshes, tliere are no superficial sense-organs on the head, and the tubes of 

 the two sides are symmetrically arranged." Omitting the last, I cannot acquiesce to any 

 of these statements. The lateral sense organs have xicdoubtedly advanced purl passu 

 A\ith the development of the skull and the evolution of the asymmetry of the Pleuro- 

 nectidge. Cunningham's figure of the sensory canals of the Cod is copied " with slight 

 modifications " from the figure given by Traquair in his Pleuronectid paper. Traquair's 

 figure, as far as it goes, is perfectly accurate, and I must confess that Cunningham's 

 modifications are somewhat unfortunate — especially the one that connects the liyo- 

 mandibular with the lateralis canal. Further, the statement as to the absence of 

 superficial sense organs is a curious oversiglit, especially as the mandilnxlar line of pit 

 oi'gans is more obvious than these organs are in any other fish I am acquainted with. 



Allis, in his last Amia paper (1S97, 6), makes some passing references to Gadus, which 

 he states are based on work being done in his laboratory by Dr. Dewitz and Mr. Samuel 

 Mathers. On p. 631 he says : — " In Gadus there is a line of surface organs on the outer 

 surface of the opercular bones immediately behind the preoperculum. They are all 

 innervated by a special branch of the mandibularis externus facialis, and are therefore 

 of the character of pit organs, and unquestionably represent in Gadus one of the cheek- 

 lines of Amia or a similar line not found in Amia." Again, on pp. 032-633: — '' h\ 

 Gadus a line of surface organs is found along the lower edge of the mandible, parallel 

 to the mandibular canal, and it is innervated by a long branch of the externus facialis, 

 which first runs forward through the adductor mandibuUe, to tlie hind edge of tiie 

 infraorbital canal behind the eye, and there turns downwards and reaches the mandible. 

 A nerve in Esox corresponding in position to this nerve in Gad/is innervates a line of 

 surface organs lying on the upper jaw immediately below the infraorbital canal." 

 Respecting the innervation of the latter organs lie says (p. 637) : — " Tiiis nerve [/. e. a 

 branch of the externus facialis] in Silurus may l)e a l)ranch cori-esponding to the one 

 which in Amia innervates the mandibular line of pit organs, and in Gadus innervates 

 a mandibular line of the slit like organs peculiar to that fish." 



Finally Goronowitsch (1897, 90) has given an admirable account of the trigemino- 

 facial complex of JLoia vulgaris, in which tlie histology of the medulla and the nerve 

 tracts of the ganglionic complex are ably elucidated and described. 



It is thus seen that our knowledge of the lateral sense organs and their associated 

 nerves in Gadus is still of a vei'y imperfect description, and in fact all the work of any 

 pretension was done before the lateral line system w'as properly understood, and l)efoie 

 the researches of Allis, Ewart, and Strong had placed our knowledge of this interesting- 

 system on a secure basis of carefully ascertained fact and logical deduction. It is the 

 purpose of the present communication to supply this defect, to add some new facts 10 

 our knowledge of the lateral organs, and jJerhaps to elucidate many points that are still 

 somewhat obscure. I find with Allis that " as the work has j)rogressed it has repeatedly 



