526 THE SOLIDS. 



lamina (Plate LXIX. fig. 3.), from a beautiful series of 

 teeth, forming its outer margin, which project far into the 

 vestibular scala, and, in the first coil, terminate almost on a 

 level with the margin of the osseous zone, but more within 

 this margin towards the apex of the cochlea. They thus con- 

 stitute a kind of second margin to the osseous zone, on the 

 vestibular side of the true margin, and having a groove 

 beneath them, which runs along the whole lamina spiralis, in 

 the vestibular scala, immediately above the true margin of 

 the osseous zone. The intervals between the teeth, are to be 

 seen on their upper surface, on their free edge, and also 

 within this groove, so that the teeth are wedge-shaped, and 

 their upper and under surfaces, traced from the free edge, 

 recede. The free projecting part, or teeth of the denticulate 

 lamina, form less than a fourth of its entire breadth, and in 

 the remainder of its extent, it appears to rest on the osseous 

 zone ; seen from above, after the osseous zone has been ren- 

 dered more transparent by weak hydrochloric acid, rows of 

 clear lines may be traced from the teeth at the convex edge, 

 towards the opposite or concave edge of the lamina. These 

 lines appear to be a structure resembling that of the teeth 

 themselves, and they are separated from one another by rows 

 of clear, highly refracting granules, which render the inter- 

 vals very distinct. These intervals are more or less sinuous 

 and irregularly branched. 



" The denticulate lamina, thus placed on the vestibular 

 surface of the osseous zone, is above, and at some distance 

 from the plexus of the cochlear nerves, which lies near its 

 tympanic surface. The vestibular surface of the osseous zone, 

 including the denticulate lamina, is convex, rising from the 

 free series of teeth towards the modiolus. 



" In the groove already mentioned, there is a series of elon- 

 gated bodies, not unlike columnar epithelium, in which the 

 nuclei are very faint. 



" These bodies are thick and cubical at one end, and taper 

 much towards the other. They are united in a row, and it 

 is possible they may have some analogy to the club-shaped 

 bodies of Jacob's membrane. We can assign them no use. 



