ON LOXOMMA ALLMANNI. 391 



good state of preservation, and exhibits in great perfection, co- 

 vering the whole of the upper aspect, the peculiar honeycombed 

 or reticulated structure common to these Labyrinthodonts. The 

 roof of the mouth is also well displayed, particularly the sphe- 

 noid and the vomerine and palatal bones, likewise the posterior 

 nares and the palato-temporal foramen. The basal portions of 

 the teeth, too, are nearly all present ; but the crowns, unfortu- 

 nately, have disappeared. 



In every respect the characters agree with those of the previ- 

 ously described specimen ; and in addition, the parietal foramen 

 is distinctly marked in the new example. This characteristic 

 feature is not seen in either of Mr. Thomson's specimens ; but 

 in the original cranial fragment described by Professor Huxley 

 it is well indicated on the inner surface.* In our specimen it is 

 small and circular, measuring not much over an eighth of an 

 inch in diameter. It is placed near the centre of the wide occi- 

 pital portion of the median coronal bones. The mucus grooves 

 on the muzzle, too, are well developed : one passes straight 

 across the premaxillaries in front ; from either end of this, and 

 forming with it an acute angle, another groove passes backwards 

 for a considerable distance along the side of the muzzle. 



The teeth are nearly all present in a more or less imperfect 

 condition ; mostly, however, the stumps only remain. There 

 are three pairs of large tusks — one vomerine, two palatal. The 

 vomerine tusks are situated about one inch and a quarter behind 

 the anterior margin of the prgernaxillse ; the basal portions of 

 these project considerably, and measure in diameter three quar- 

 ters of an inch. The first pair of palatal tusks are placed two 

 inches further back, and are scarcely so large as the vomerines ; 

 the second pair, which seem equally large, are one inch and a 

 quarter further in the rear, being somewhat in front of the trans- 

 verse centre of the skull. Each prasmaxilla bears four teeth, 

 which are upwards of a quarter of an inch wide at the base. 

 There are five or six rather smaller teeth behind the vomerine 

 and the first palatal tusk, and the like number between the lat- 

 ter and the second palatal tusk ; and behind this, again, there 



Quarterly Journal of the Geological Society, 18C2. Vol. XVIII.. p. 201 



