from the Marl-Slate of Midderidge. 61 



a space between them less than half their diameter. Thej are 

 in the form of irregularly rounded bosses, with the surface 

 smooth and glossy, and the margins sinuous and produced into 

 points. Sometimes, however, they are much elongated, and 

 are frequently very irregular in shape, with the marginal pro- 

 longations much produced, variously formed, sharp or obtuse. 

 Others have one margin comparatively smooth, the points 

 being conliued to the opposite side. Some are quite devoid of 

 all such irregularities, the margins being smooth or only a 

 little sinuous at one side ; these are rounder and larger than the 

 others (fig. 8). Another form (fig. 7), not by any means un- 

 common, is irregularly stellate, with the rays ridged and some- 

 times a little bifurcated. 



From the fineness of the cutting-margin in the so-called 

 Climaxodus, it was inferred in the former paper, so frequently 

 referred to, that the food must have been composed of some soft 

 material. We .are disposed to draw the same conclusion from 

 the structure of the teeth ofJanassa hituminosa. The scoop-like 

 cutting-margin is certainly much used, for it is almost always 

 greatly worn in a regular manner ; only in one instance have 

 we seen it a little broken. It would be an efficient instrument 

 in cutting vegetable substances, and these might afterwards 

 require the aid of the crushing-disk. 



In corroboration of this view of the food, we may quote a 

 passage from Miinster, who says, of his Byzenos latipinnatus, 

 that " the intestine seems to have been very full when the 

 fish died. It is more elevated than the other parts of the body. 

 On some places one sees in the interior a black earthy mass 

 in which small pointed bodies appear, which are like small 

 pieces of shiny coal." May not this " black earthy mass " 

 and " pieces of shiny coal " be carbonized vegetable matter, 

 the food of the fish ? 



It is unnecessary here to dilate on the affinities of Janassa, 

 as the subject is discussed in the former paper, already quoted. 

 We may remark, however, that the full investigation of the 

 Permian species has only the more confirmed our opinion of 

 its close alliance with tlie Coal-measure form (the so-called 

 CUmaxodus Unguaformis) , and of a certain relationship of 

 both to Myliohates and Zygohates. 



We may also state that Janafisa is more closely related to 

 Petalodus than was at first thought ; for we now find that the 

 latter genus is provided with both symmetrical and oblique 

 teeth ; so that it is quite probable that they may be found to 

 be arranged in much the same manner as those of Janassa, 

 especially as the former have been found in vertical series, as 

 previously stated. 



