BY J. DOUGLAS OGILBY. 161 



'dentition of our fish, in which the teeth would more correctly be 

 termed tubercular, and form in fact a smooth pad-like surface, 

 ■which entirely covers the jaws, both outside and inside, palatines, 

 pterygoids, and branchial arches, and partially the vomer and 

 tongue. 



There is no reference in any of the authors above mentioned to 

 the curious bifurcation of the dentary nor to the luminous man- 

 dibulary disc, the presence of which is, however, the obvious 

 cause of the departure from its ordinary form which has taken 

 place in that bone, since the supplementary external limb has 

 been manifestly provided for the protection of the sensitive light 

 glands, the teeth with which it is armed beinijj of little or no use 

 in such a position. The presence of luminous glandular discs, as 

 such, is not in fact referred to anywhere, though Cuvier and 

 Valenciennes, in their excellent account of the Japanese fish, 

 speak of these discs as colour-markings, not recognising their 

 true character. In addition to these mandibulary discs, there 

 are, as mentioned in the diagnosis of the family, three other discs, 

 namely, the maxillary disc, situated at the bottom of the symphy- 

 sial cavity, and the two preorbital discs, covering the postero- 

 superior angle of the largely developed cranial canal, which 

 uninterruptedly pierces the rostral framework from side to side 

 in front of the eyes. There is no apparent necessity for this 

 latter pair of luminous discs, unless they are provided for the 

 purpose of disseminating light immediately in advance of the 

 visual organs; but with the three remaining discs the case, as it 

 appears to me, is very different, for I think we may fairly con- 

 clude that these luminous glands serve as traps to entice their 

 prey within reach; some such provision would, in fact, be neces- 

 sary to a species which, having regard to the small size of the fins 

 and the comparative inflexibility of the dermal incasement, must 

 needs be possessed of but feeble swimming powers, and the 

 position of the maxillary and mandibulary discs fully supports 

 the legitimacy of this deduction. For, while the glow of the 

 maxillary organ, set as it is in the recess of a cup-shaped cavity, 

 would only be visible to a creature stationed or passing directly 

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