132 RECORDS 



tributing to the manubrium mallei, and a membrane bone which 

 forms the Fallopian process. Furthermore, as Gegenbaur points 

 out, the continuity of malleus and incus, if they be the quadrate 

 and articular, is itself in contradiction to the independent embry- 

 onic origin of these elements in the lower forms. The pretre- 

 matic origin of the ossicles in the pig, as described by Kingsley, 

 is contrasted with their postrematic, or hyoidean, origin in lower 

 forms. Dr. Weil stated that his studies of a full series of pig 

 and opossum embryos did not enable him to decide whether the 

 malleus, and still more, the incus, lay primarily in front or behind 

 the tube. The bones cross the anlage of the tube in a trans- 

 verse direction, lying above it ; by the gradual absorption of the 

 intervening stroma they come to occupy the cavity of the tym- 

 panum. Finally, the innervation of the tensor tympani muscle 

 of the malleus by a branch from the otic ganglion of the trigem- 

 inus is taken to indicate the relation of the malleus to the man- 

 dibular arch. But lesions of the trigeminus at its root do not 

 involve hearing, while the contrary is true of lesions of the facial. 

 This fact would point to the origin of the above-mentioned 

 nerve from the seventh nerve, and would make the malleus a 

 part of the second arch. The second contention is supported, 

 first, by the difference in the embryonic relations of the bones to 

 the Eustachian canal, an argument already considered, and second, 

 by the differences in the relations of the chorda tympani nerve, 

 which in Sauropsida crosses above the chain, and in mammalia 

 below it. The speaker showed that the pathologists, from a 

 comparison of a large number of lesions of the trigeminus and 

 of the facial at the base of the brain, had demonstrated the exit 

 of the chorda tympani in man with the roots of the former. But 

 since it leaves the brain in lower forms with the seventh, its re- 

 lations to bony structures are evidently not sufficiently constant 

 to constitute a criterion of homologies. From these facts, it 

 would appear that the homology of malleus and incus with the 

 quadrate and articular has not yet been demonstrated. 



Dr. Mayer showed that the snails in question are subjected 

 to conditions of isolation very similar to those affecting the 

 Achatinellidae of Oahu in the Hawaiian Islands, occurring in 



