217 



Nachdruck verboten. 



Notes on the Auditory Organ and the Orbit of 

 Orthagoriscus mola. 



By Alexander Meek, M. Sc, 



Durham College of Science, Newcastle-upon-Tyne. 



With 4 Figures. 



I have to thaok Mr. Crisp, St. Mary's Island, for his kindness 

 in presenting to me a small Sun-fish, which he caught in his salmon 

 nets in July, last year. Its length was only 53 cm, the depth in front 

 of the median fins 34 cm, and it measured from tip to tip of these 

 fins 76 cm. 



Auditory organ. It gave me the opportunity of re-examining 

 the auditory organ. In 1888, in Dundee, I dissected the ear of a 

 Sun-fish measuring 1,35 m, and my notes and drawings were published 

 by Professor D'Arcy W. Thompson ^). I would not have referred to 

 it again, for the specimen now under review bears out exactly the 

 description given for the Dundee specimen, if a mistake of some mor- 

 phological importance had not crept into the paper mentioned. 



Professor Thompson said: "A single vertical pillar of cartilage 

 passes down across this space within the arc of the horizontal canal. 

 (In Harting's specimen another passed within the arc of the anterior 

 vertical canal.)" In the Dundee example a pillar, reduced however 

 to a distinct fibrous band, passed through the arc of the posterior 

 vertical canal ; and in the case of Harting's specimen a cartilaginous 

 pillar passed, not through the space enclosed by the anterior vertical 

 canal, as Professor Thompson wrongly stated, and it would have been 

 remarkable if it had, but through the arc of the posterior canal. In 

 the present example I find the conditions to be exactly as they were 

 in the Sun-fish I dissected at Dundee, with the exception that the 

 horizontal pillar is cartilaginous, and in this and other respects it 

 bears out the drawing given by Harting^), 



As in these cases, the ear lies in a wide auditory capsule lined 

 by a tough membrane continuous with the dura mater and traversed 



1) Anat. Anz., Jahrg. 3, 1888, p. 93, republished in the Studies 

 from Museum of Univ. Coll., Dundee, 1889, No. 4. 



2) P. Harting, Not. zool., anat. et hist, sur I'Orthagoriscus ozodura. 

 Verh. d. Kon. Akad. v. Wet., Deel 11, Amsterdam, 1868. 



