340 MESSES. HANCOCK AND HOWSE 



(Petrefactenkunde, p. 39) ; and in 1823 two figures were given 

 by this author, in his " Nachtrag" ii., tab. 22, f. 9 a, 9 b. 



Between the years 1833-1843, Count Miinster figured and de- 

 scribed numerous examples of the strongly characterized teeth 

 and the shagreen skin of this peculiar fish under two or three 

 generic and five or six specific names. These teeth were by 

 him supposed to be palatal (an opinion which seems to be enter- 

 tained by later German authors), and to belong to a fish of the 

 Placoid order. After carefully examining the descriptions and 

 figures given by Count Miinster, we fully agree with those 

 writers v/ho consider that the foUov/ing references belong all 

 to one species, and we also are quite assured that the specimens 

 obtained from the English Marl-Slate are perfectly identical with 

 those described by this author in his Beitrage zur Petrefacten- 

 kunde : — Heft i. Janassa angulata, p. 67, Taf. 4, f. 1, 2 ; J. 

 Humholdii, p. 122, Taf. 14, i.4; J. bituminosa, Schloth., p. 122. 

 Heft iii. J. angulata, p. 122, Taf. 3 & 4, f. 5 a ; Dictea striata., 

 p. 124, Taf. 3 & 4, f. 1, 3, 4 ; Taf. 8, f. 3, 4, 6, 7, 8, 9, 10. 

 Heft V. Janassa dictea, pp. 37-39, Taf. 15, f. 10-16. Byzenos 

 latipinnatus, Heft. vi. p. 50, Taf. 1, f. 2. 



About the same time Janassa was briefly described by Agassiz 

 under the name of Acrodus larva, Poiss. Foss. iii. pp. 147, 174, 

 376, tab. 22, f. 23-25 ; and this learned author for the first 

 time pointed out the probable afiinities of these remarkable fish- 

 remains. 



Later Grerman authorities, and especially our friend Dr. Gei- 

 nitz, had already arrived at the conclusion that the various spe- 

 cies of Janassa and Dictea described by Count Miinster must all 

 be brought back to one form, to which, by right of priority, 

 Schlotheim's specific name should be attached. Indeed Dr. 

 Geinitz has so recently (Dyas, 1861) examined and carefully 

 commented on the various species described by Count Miinster, 

 that we think it better to give a translation of his remarks than 

 to offer detailed ones of our own, especially as Dr. Geinitz would 

 have the advantage of seeing many of the German specimens, 

 and as we do not, excepting in one or two points, differ in opin- 

 ion from the conclusions arrived at by this excellent naturaUst. 



