Licence: Public Domain Mark
Credit: A manual of dental anatomy : human and comparative / by Charles S. Tomes. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
28/614 (page 14)
![that the outer layer are not only inclined upwards but also sideways towards the middle line of the head; thus the middle line of the head would he above the section as represented. As regards the decussation of the prisms of alternate layers, it is similar to that of the Sciuridce, but it differs in tlic lamiuic being slightly flexuous instead of pur- suing perfectly straiglit lines. In the porcupine family very much more complex j^atterns are met with, the enamel prisms being individually flexuous, and their curves not being confined to one plane ; the indi- vidual prisms pursue a serpentine course, and cannot be followed far ni any one section. Near to the surface, how- ever, they all become parallel, the enamel thus conforming with that of other rodents in being divided into two portions (at least so far as the course pursued by, and the pattern traced by, its fibres in its inner and outer parts can be said to so divide it). The Leporidie, or hai'cs, form an exception ; Fu;. 3(>). their enamel has no such lamelliform arrangement, hut is built U]j merely of slightly flexuous prisms. By tracing the courses of enamel prisms from the simple (') Human enamel, from the masticating surface of a mol:ir. Tlic figure is merely intended to show the general direction of the iil>re.s.](https://iiif.wellcomecollection.org/image/b21932025_0028.jp2/full/800%2C/0/default.jpg)
