238 
ACTINOPTERYGII. 
of its basal cartilages; Kelheim. The supposed sclerotic 
seems to exhibit a few sparse and fine granulations as in 
the last specimen. Egerton and Enniskillen Colls. 
P. 3768 a. Very small, immature fish, wanting the caudal region; 
Kelheim. Though much crushed, this specimen is in¬ 
teresting as exhibiting a thickened bar behind the 
operculum, extending from the normal upper limit of the 
clavicle to the back of the cranium, thus probably a 
supraclavicle. Seven basals are preserved in the pectoral 
fin. Enniskillen Coll. 
Gyrodus circularise Agassiz. 
1833. Sphcerodus rhomboidalis, L. Agassiz, Poiss. Foss. vol. ii. pt. i. 
p. 15 (undefined). 
1834-44. Gyrodus circularise L. Agassiz, Poiss. Foss., Feuill. p. 18 
(name only), and vol. ii. pt. ii. p. 300. 
1834-44. Gyrodus punctatissimus, L. Agassiz, ibid. Feuill. p. 18 (name 
only), and vol. ii. pt. ii. p. 301. [Fragment of fish; Palaeontological 
Museum, Munich.] {—Microdon gigas , Agass. MS.) 
1834-44. Gyrodus rhomboidalis, L. Agassiz, ibid. Feuill. p. 18 (name 
only), and vol. ii. pt. ii. p. 300. [Imperfect fish ; Palaeontological 
Museum, Munich. 1 
1836. Gyrodus multidens, G. von Munster, Neues Jahrb. p. 581. 
[Imperfect head ; Palaeontological Museum, Munich.] 
1845. Gyrodus umbilicus, Mandelslohe, Wiirtt. Jahresh. vol. i.p. 153, 
fig. 2. 
1851. Gyrodus circularis, A. Wagner, Abh. k. bay. Akad. Wiss., math.- 
phys. Cl. vol. vi. p. 10, pi. i. fig. 1. 
1851. Gyrodus rhomboidalis, A. Wagner, ibid. vol. vi. p. 19, pi. i. fig. 2. 
1851. Gyrodus multidens, A. Wagner, ibid. vol. vi. p. 23, pi. i. figs. 3, 4. 
1851. Gyrodus punctatissimus, A. Wagner, ibid. vol. vi. p. 27. 
1855. Gyrodus umbilicus, O. Fraas, Wiirtt. Jahresh. vol. xi. p. 100. 
1862. Gyrodus titanius, A. Wagner, Abh. k. bay. Akad. Wiss., math.- 
phys. Cl. vol. ix. p. 331. [Founded on the type specimen of 
G. circularis, Ag.] 
1862. Gyrodus giganteus, T. C. Winkler, Descript. Poiss. Foss. Solen- 
hofen (Natuurk. Verhandl. Holland. Maatsch. [2] vol. xiv.), p. 80, 
figs. 13-15. [Nearly complete fish ; Teyler Museum, Haarlem.] 
1867. Gyrodus titanius, F. A. Quenstedt, Handb. Petrefakt. ed. 2, 
p. 254. 
1881. Gyrodus titanius, B. Vetter, Mittheil. k. mineral.-geol. Mus. 
Dresden, pt. iv. p. 21. 
1887. Gyrodus titanius, K. A. von Zittel, Handb. Palaeont. vol. iii, 
pp. 242, 243, figs. 253, 255-257. 
Type. Nearly complete fish; Palaeontological Museum, Munich. 
A large species, attaining a length of about 1*0. Maximum 
