ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xiii 



He also showed that the greater half of the common bile duct lay 



between the duodenum and pancreas. 



He showed that many of the duodenal diverticula at the opening of 



the common bile duct were due to pressure, appHed by corsets to^the 



liver, forcing the duodenum, pancreas, and kidney out from beneath the 



liver. The duct, being inelastic and stout, could not be stretched ; 



the mucous membrane and bowel wall being the weaker, gave way- 

 He regarded ptosis of the liver, Eiedel's lobe of the live'r, gall stone, 



floating kidney, and duodenal diverticula as correlated' conditions 



found in ' corset disease.' 



(9) Dr W. H. Gaskell, F.R.S., read a paper on the Origin of the 

 Vertebrate Ear and Auditor// Pair of Nerves. This paper will be 

 published in full at a future date. 



_ Dr Gaskell pointed out that he had already laid before the Society 

 his views as to the meaning of all the cranial nerves, with the excep- 

 tion of the auditory. The position of this latter nerve was not so clear 

 as that of the rest of the cranial nerves. The auditory organ marked 

 a line of separation between the pro-otic and opisthotic group of 

 cranial nerves, i.e., between the prosomatic and mesosomatfc group, 

 according to his theory. Somewhere in this region, then, a special 

 sense organ must have existed in the ancestors of the vertebrate 

 which belonged to an appendage, was innervated by a portion of the 

 appendage nerve, and possessed a peripheral ganglion. The author, 

 therefore, made search in this region in Limulus and the scorpion group' 

 and discovered in the former a most elaborate sense organ in the'shape 

 of the flabellum, which is connected with the last prosomatic locomotor 

 appendage, while in the latter, as is well known, a remarkable sensory 

 organ has long been known to exist, called the pecten. He then pro- 

 ceeded to describe the structure of the tiabellum, and to show how it 

 compared with the poriferous chordotonal organs described by Graber 

 in insects — organs which are uniformly situated on the fore and hind 

 wings, and are innervated therefore by dorsal nerves. These organs 

 in the Diptera attain so great an importance that the balancers or 

 halteres which represent the hind wings possess no powers of locomo- 

 tion, but constitute an elaborate sense organ which, as experiment 

 proves, is concerned with equiUbration, and is generally supposed to 

 be auditory in function as well. It is very possible, in fact probable, 

 that the pectens of the scorpion, as well as the racket-shaped organs 

 found on the basal joints of the last pair of prosomatic appendages 

 in Galeodes, belong to the system of lyriform organs which appear°in 

 Arachnids to take the place of the chordotonal organs in insects, and are 

 supposed to have the same function of audition. According to Kish- 

 inouye, a series of organs similar to the flabellum are seen in the 

 embryo Limulus on all the prosomatic appendages. Of these the 

 flabellum alone develops xip to the adult condition. On the meso- 

 somatic appendages are found also striking sense organs, with a very 

 fine central chitinous pore which, as their structure suggests, may be 

 pressure organs for estimating depth of water, so that it' is quite 

 probable that the flabellum of Limulus may be a specially developed 



