THE ATTACHMENT OF TEETH 363 



angler for pike knows that the fish may often be held for 

 a considerable time and "even drawn out of the water when 

 not hooked, the retention of the living bait between the 

 teeth being so complete that it cannot be withdrawn. The 

 above-named author found examples of hinged attachment 

 in many specimens of deep-sea fish obtained on the Challenger 

 expedition. 



(3) Anchylosis. This is the more common form of attach- 

 ment in fish and reptiles ; there is no intervening vascular 

 and fibrous membrane, and the union does not take place 

 directly with the bone of the jaw, but through the medium 

 of the bone of attachment. The fusion of the tooth with 

 the bone of attachment is usually very complete, so much so 

 that, as C. S. Tomes points out, in grinding a section of an 

 anchylosed tooth the bone of attachment often comes away 

 from the bone, while it is firmly attached to the tooth 

 (fig. 236). 



A curious modification of this mode of attachment is 

 seen in the Mackerel, where the tooth is anchylosed to the 

 bone at its lateral margins but unattached below, being, as 

 it were, slung within the bone. 



The author in an examination of two species of Wrasse 

 (Labrus) found a curious modification of anchylosis in these 

 fishes. The tooth when about to erupt has a large pulp 

 cavity with the usual dentine pulp consisting of connective 

 tissue and blood-vessels and a layer of large odontoblasts. 

 The pulp is extremely vascular and the vessels form a con- 

 tinuous network of loops within the odontoblast layer in 

 close contact with the tubular dentine. The pulp tissue is 

 seen to merge into bone beneath the open end of the rootless 

 tooth. When the tooth is erupted and the deposition of 

 the dentine is completed, the bone tissue invades the pulp 

 chamber and entirely fills it, the bone becoming continuous 

 with the dentine around the inner margin of the pulp, the 

 odontoblasts having entirely disappeared. 



This is not the same condition as in the anchylosed 

 teeth of the Pike, where the tissue of the tooth is an osteo- 

 dentine, but an actual substitution of the dentine-forming 

 pulp by true bone (figs. 241 and 242). 



Anchylosis is found in the teeth of the Python and the 



