2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 74 



Sullivan Island, but unfortunately its head is injured and the mouth 

 is not well preserved. The skulls, after partial fleshing, were treated 

 with salt. The}' arrived at Washington in a slightly moist condi- 

 tion, and the gums, when soaked in fresh water and subsequently 

 placed in alcohol, appear to have retained much if not all of their 

 original structure. 



The general appearance of the gums as viewed from the outer side 

 is shown in Plate 2 (natural size). It will be seen that, along the 

 entire course of the tooth row, except at the front, where some injury 

 has been suffered, the gums stand up as a serrate-topped, raised 

 mass, which, in the uninjured region extending backward from the 

 middle of the row, entirely conceals the teeth. Probably in a fresh 

 specimen with perfect gums no teeth would be visible anywhere in 

 the series. 



Photographs of segments containing four teeth are shown, five 

 times natural size, in Plates 3 and 4. The gross structure of the 

 gums and the relations of the true teeth to the new prehensile appa- 

 ratus may be seen with special clearness in the series of four mandib- 

 ular teeth represented in Plate 3, In the outer view (a) the gum 

 has been injured at one point so that the flat crown of the second 

 tooth from the left is visible at the bottom of the angular cleft be- 

 tween the bases of the first and second complete gum teeth. All 

 the other true teeth are hidden in this view as well as in that from 

 the inner side of the jaw (&). In the coronal aspect (a) the sum- 

 mits of the four true teeth are seen at the bottoms of their pits, with 

 the four alternating gum teeth occupying the areas between them. 

 In Plate 4 we have a segment of the rostrum including four teeth 

 and extending inward nearly to the median line of the palate. It 

 is shovvn in palatal aspect (a) and vertical section (6). The gum 

 teeth are foreshortened and flattened by the camera in the palatal 

 view, but their height is well brought out in the vertical section. 

 It will be noted that the entire surface of the palate is coarsely and 

 irregularly wrinkled, the general direction of the broad ridges and 

 narrow intervening furrows tending to be parallel with the tooth row ; 

 also that the profile of these secondary ridges, Avhen viewed in cross 

 section, resembles the corresponding profile of the functional gum 

 teeth. The gum surface as seen on the palate (pi. 4a) and on the 

 inner side of the mandible (pi. Sh) is noticeably papillose. In cross 

 section under this low magnification the papillae appear as conical 

 outgrowths from the substance of the ridges. 



Microscopical preparations, made bj^ staining and sectioning a 

 23iece of one of the gum teeth at the Anatomical Laboratory of the 

 Johns Hopkins Medical School,'' show that the elevations are dermal 



* I owe this series of slides to the kindness of Dr. George B. Wi.«locki. 



