APPENDIX.

117

Genus Agnostus, Brongn . (Battus, Dalman.)

Cephalic shield (Table V, Fig. 7) equally large as, or a little smaller than the caudalshield, similarly formed, very convex, margin elevated, or uniformly declining at the circum-ference, the axis more or less distinctly marked, narrower towards the front, provided theextremity be not very much enlarged, as it is in a new species Agn. Rex, Barr. Thisextremity is usually marked by a distinct transverse furrow ; the basal part is not divided, orif so, at the utmost only by two small lateral lobes.

Facial suture and eyes not perceptible.

Body two-jointed, the axis of the joints depressed, broader than the furrowed laterallobes.

Caudal shield (Tab. V, Fig. 6) usually rather broader, although not longer than thecephalic shield, the lateral margin rather less elevated, frequently ornamented with twomarginal points; the axis considerably prominent, distinctly divided, usually furnishedwith an elevated longitudinal callosity, and two oblique lateral furrows, which extendtowards the axis, and separate its rather broader extremity in the manner of a glabella. Atthe commencement of the axis there is a distinctly projecting marginal articulate fold.

Their power of rolling themselves up has not yet been ascertained.

Locality .—In the lower Silurian strata. The species have not yet been satisfactorilyestablished, but there appear to be several.

1. A. pisiformis, Tab. V, Fig. 7, cephalic shield; Fig. 6, caudal shield. Brongn .Crust, foss. 38, PI. IV, Fig. 4, a, B. Bronn. Lethcea geogn. i, 123, Tab. IX, Fig. 20.Murchis. Sil. Syst. ii, 664, PI. XXV, Fig. 3. Milne Edw. Crust, iii, 348. 1. Gr. v.Munster, Contrib. 111,47. 1. Goldf. Leonh. and Bronn. New Annual, 1843, 542. 1.Trilob. pisif. Schloth. Petr. Suppl. II, 36, 21. 26, 1. Battuspisif. Dalm. Palcead. 57. IV. 1 ;75. V. 1. Hising, Leth. Suec. 19, Tab. IV. Figs. 5, 6. Linn. S. Nat. iii, 160, 161.(ed. 12). Bromell, Act. lit. Ups. 1729, 526. 4. c Fig. Wilkens, Verst. 75. Tab. VII,Figs. 38, 39. Modeer, Schrift d. Naturf. Freunde z. Berlin, 14, 248. Tab. II, Figs. 1, 2.

Locality .—In the alumslate and stinkstone of Andrarum, at the Kinnekulle, etc., andin similar strata in England.

2. A. leevigatus. Dalm. Arsberdth. 1828. 136. Hising. Leth. Suec. 20. 2. Goldf. /. c.542. 2. At the Kinnekulle, near Honsater.

3. A. integer. Battus integer, Beyr. on Bohemian Trilobites, 44, 1, Fig. 19. In thelower Silurian strata of Bohemia.

4. A. nudus. Battus nudus, Beyr. as above, 46. Fig. 20.

Remark. —My figures of A. pisiformis (Table V, Figs. 6, 7), owing to the fault of the artist,were not formerly quite true to nature, and they have therefore been somewhat altered, so that theynow certainly appear different, hut decidedly more correct, although even now the shades of thefurrows may perhaps be rather too deep. The smaller forms (formerly Figs. 5 and 8) do not deviateso materially as to render a particular representation of them necessary, and they have therefore beenset aside to make room for other figures of more consequence.