A. Smith Woodivard — On the Genus Notidanus. 209 



There seems to be no undoubted reference to teeth of this type 

 since Agassiz' original description, though the name is mentioned 

 in several lists of Continental Jurassic fossils. The specimens from 

 Schnaitheim figured by Queustedt as N. Miinsteri are almost cer- 

 tainly referable to a distinct form next to be considered. 



3. N. eximius, Wagner. PI. VI. Figs. 3 — 5. 



1849. JV. Miinsteri, Beyrich and Frischmann, Zeitschr. Deutsch. Geol. Gesell. vol. i. 



p. 436, pi. vi. 

 1852. „ „ F. A. Quenstedt, " Handb. Petr." p. 167, pi. 13, fig. 4. 

 1858. ,, ,, F. A. Quenstedt, " Der Jura," p. 662, pi 96, figs. 33, 34. 

 1861. N. eximius, A. "Wagner, Abb., k. bayer. Akad. d. Wiss. cl. ix. vol. ix. pp. 



292-296, pi. iv. fig. 2. 



The Lithographic Stone (Lower Kimmeridgian) of Bavaria is the 

 only deposit that has hitherto yielded remains of Notidanus other 

 than detached teeth. But from this fine-grained rock at least three 

 comparatively perfect fishes have been described, in addition to one 

 other fragment of the caudal extremity. Of these, the finest speci- 

 men was figured by Beyrich and Frischmann, loc. cit:, in 1849, and 

 the subsequent studies of Dr. Andreas Wagner resulted in its being 

 separated from all other known species under the name of N. eximius. 



The important fossil just referred to was obtained from the 

 quarries of Eichstadt, and is complete with the exception of the tip 

 of the tail : it indicates an original length of about nine feet, and 

 exhibits a very definite outline, owing to the presence of plentifully 

 scattered shagreen granules in the skin. The head is rounded and 

 obtuse in front, and a considerable number of teeth are exhibited in 

 the region of the mouth. The pectoral fins are evidently larger than 

 the ventrals, and the anal is small compared with the dorsal ; the 

 latter is almost entirely in advance of the anal, although appearances 

 may be deceptive owing to pressure during fossilization. But the 

 most remarkable character displayed in this specimen is the presence 

 of well-marked annular cartilages in the sheath of the notochord. 

 These have been carefully studied by Dr. Hasse, 1 of Breslau, who 

 has shown that they agree in microscopical structure with those of 

 the living Heptanchus ; and this Kimmeridgian form is thus the only 

 fossil species hitherto discovered that it has been possible to refer to 

 the correct subgenus. The vertebral rings in the caudal region are 

 further apart than in the more anterior portions of the body. 



The two other specimens of Notidanus from the Lithographic Stone 

 are of small size, not exceeding 4^ inches in length, and are regarded 

 by Wagner as probably the young of the species under consideration. 

 No figures have been published, but a plaster cast of one of these 

 immature fishes is exhibited in the British Museum. 



A group of the teeth of N. eximius are figured by Beyrich and 

 Frischmann, and Wagner also represents a solitary example. The 

 drawings of the Eichstadt fossil, however, do not appear to illustrate 

 the variation of the dentition in different parts of the mouth, nor do 

 the authors offer any particular observations upon this point. In 



1 C. Hasse, " Natiirl. Syst. Elasm.— Besond. Theil," pp. 51, 52, pi. vii. figs. 23-25. 



DECADE III. VOL. III. MO. V. 14 



