SEMIOXOTIDiE. 
159 
1835. Tetragonolepis semicinctus , L. Agassiz, Poiss. Foss. vol. ii. pt. i. 
p. 196, pi. xxii. figs. 2, 3. 
1842. Tetragonolepis subserratus, G. von Munster, Neues Jahrb. p. 97. 
[Imperfect fish ; Palaeontological Museum, Munich.] 
1843. Tetragonolepis semicinctus, F. A. Quenstedt, Flozgeb. Wiirttemb. 
p. 240. 
1852. Pleurolepis semicinctus , F. A. Quenstedt, Handh. Petrefakt. 
p. 214. 
1853. Tetragonolepis subserratus =T. semicinctus (?), Sir P. Egerton, 
Quart. Journ. Geol. Soc. vol. ix. p. 277, pi. xi. fig. 3. 
1853. Tetragonolepis cyclosoma, Sir P. Egerton, ibid. p. 278. [Imperfect 
fish; British Museum.] 
1858. Tetragonolepis semicinctus, F. A. Quenstedt, Per Jura, p. 229 , 
pi. xxix. fig. 5. 
1860. Pleurolepis semicincta, A. Wagner, Gelehrte Anzeig. k. bay 
Akad. Wiss. yol. 1. p. 94. 
1883. Pleurolepis semicinctus, F. A. Quenstedt, Ilandb. Petrefakt. 
ed. 3, p. 323. 
1892. Tetragonolepis semicinctus, 0. M. Peis, Geogn. Jahresh. 1891, 
p. 160, fig. 11. 
Type. Fish, imperfect anteriorly. 
The type species, attaining a length of about 0*1. The maximum 
depth of the trunk five times as great as the depth of the caudal 
pedicle, and contained one-and-a-half times in the total length of 
the fish; the greatest depth of that portion of the trunk below the 
vertebral axis equalling about three times that of the portion above 
the axis. Head with opercular apparatus occupying nearly one- 
quarter of the total length ; external bones feebly tuberculated; 
marginal teeth slender. Scales smooth, or with slight rugae following 
the concentric lines of growth, the hinder border serrated ; those 
of the flanks very deep, and the ventral ridge-scales finely denticu¬ 
lated. 
The best figure of this species hitherto published is given by 
Quenstedt, Der Jura, pi. xxix. fig. 5. 
Form. Q Loc. Epper Lias : Wiirtemberg and Bavaria.9/3 ? 
16369. Imperfect head and trunk with remains of the paired fins; 
Ohmden, near Boll, Wiirtemberg. The squamation is 
almost entirely removed in the caudal region, and some of 
the laminar appendages of the neural spines are shown. 
Purchased , 1842. 
32524. Similar specimen wanting all the fins, but displaying some 
of the teeth ; Boll, xlppearances in the axial skeleton of 
the trunk suggest either that the neural and haemal 
