ON JANASSA BITUMINOSA. 343 



roots (Dyas, tab. 4, f. 5, c, and tab. 5, f. 1), and from the perfectly 

 similar arrangement of the teeth in J. angulata, J, Dictea, and 

 J. Humbolclti, Miinster, with that in our figures, which cannot 

 be recognized in Mtxnster's ideal and quite incorrect figure (Beitr. 

 iii. tab. 3 & 4, f. 2), there can exist no doubt whatever as to the 

 identity of both genera and the five different species in them. 



**In Dictea striata, Miinster (Beitr. iii. tab. 3 & 4, f. 1), the 

 whole contour of the fish appears before us, though the swim- 

 ming-appendages which surround the body permit a different 

 explanation, because this specimen lies more on the belly. The 

 length of the fish, without the caudal fin, is 0*390 metre ; the 

 height of the head 0"080 metre, the body at the pectorals, not 

 including these, 0-071 metre ; the greatest width between the 

 ventrals and the pectorals 0-110 metre, at the anal fin 0-055 

 metre, and at the base of the tail 0-035 metre broad. The whole 

 body and all the fins or swimming- enlargements are covered with 

 a fine shagreen skin. 



"The specimen shown (Dyas, tab. 5, f. 1) widens out at the 

 back of the head on each side in an arched, triangular, wing- 

 shaped, blunt process {c c), which may represent the cross-bone 

 [os transversale). 



^' Byzenos latijnnnatus, Miinster, 1843 (Beitr. vi. tab. 1, f. 2, 

 p. 50), from the Kupferschiefer of Richelsdorf, is a fragment 

 covered with fine shagreen, but which does not admit of a per- 

 fect description, and which might just as well be referred to tT. 

 hituminosa as to any other genus offish." 



With the above remarks we entirely concur, excepting the 

 statement that the teeth of Janassa are palatal, as it is proved, 

 by their relationship to Myliobates, that they are true jaw-teeth. 

 The other remark that does not appear to us satisfactory is, that 

 the two bodies designated by Count Miinster ear-bones are con- 

 sidered by Dr. Geinitz to be teeth placed near the entrance of 

 the throat. The specimens from our locality do not show a 

 trace of these peculiar bodies ; but we are disposed to consider 

 them casts of a pair of cranial cavities rather than teeth. That 

 they are not teeth seems to be clearly indicated by the entire 

 absence of enamel covering, as pointed out by Count Miinster. 



