554 



Prof. Traquair — On a New Fossil Fish. 



maxillary were wanting, as is the case in the recent Dipnoi, and 

 apparently also in the fossil JDipterus. 



A thin vertical slice, taken from the bone on the upper surface 

 near the posterior external angle, displays microscopic characters 

 essentially similar to those found in the scales and plates of many 

 ganoid fishes, including also the scales of Megalichtliys. The bone 

 is here very thin, measuring only about Vo- ii^ch in vertical section. 

 Its microscopic structure is represented in the accompanying wood- 

 cut. Immediately below the surface is an absolutely structureless 

 layer of transparent ganoine about -o-'oo- iJ^ch thick. Through this 



Vertical section of bone on the upper surface of the snout, magnified 48 diameters. 



a Layer of ganoine. b True bone. 



c Punctures of the surface — opening into the canal system of the interior. 



the punctures of the surface pass into a set of short vertical canals, 

 each widening downwards so as to assume a rather conical figure. 

 At their bases they are connected by horizontal tubes, and this 

 system also communicates below with a close irregular network of 

 ordinary Haversian canals, which ramify through the lower part of 

 the section, and, becoming coarser below, cause the bone on its inferior 

 aspect to assume almost a spongy appearance. The intervals between 

 the set of short wide vertical canals, cup-shaped in the section, are 

 seen to be each traversed by a vertical tube, which, coming up from 

 the Haversian network below, soon divide in an arborescent manner 

 into a great number of minute ramifying branches, which pass to- 

 wards but not into the superficial layer of structureless ganoine. 

 Adjacent trees of this kind also .freely communicate with each other 

 by means of arched branches, passing around and between the vertical 

 canals between which their stems are situated. A.beautiful kosmine- 

 like layer is thus formed below the ganoine ; it must be noted, how- 

 ever, that small lacunse are occasionally seen among its minute 

 tubules. In the true bone below, lacunas of the ordinary type 

 abound in the meshes of its Haversian network. 



Unfortunately nothing is known regarding the geological formation, 

 or the locality, of the fossil just described. To Mr. Davies, of the 

 British Museum, I am indebted for the information, that it " formed 

 part of the old collection of the British Museum, of which there are 

 no records, hence its history as to from whom, and whence it came 

 is wanting." Judging, however, from its general aspect, one might 

 readily be tempted to infer that it was of Palaeozoic age. 



