APPENDIX. 117 



Genus Agnostus, Brongn. (Battus, Dalman.) 



Cephalic shield (Tal)le V, Fig. 7) equally large as, or a little smaller than the caudal 

 shield, 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 the 

 extremity be not very much enlarged, as it is in a new species Agn. Rex, Barr. This 

 extremity is usually marked by a distinct transverse furrow ; the basal part is not divided, or 

 if 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 lateral 

 lobes. 



Caudal shield (Tab. V, Fig. 6) usually rather broader, although not longer than the 

 cephalic shield, the lateral margin rather less elevated, frequently ornamented with two 

 marginal points; the axis considerably prominent, distinctly divided, usually furnished 

 with an elevated longitudinal callosity, and two oblique lateral furrows, which extend 

 towards the axis, and separate its rather broader extremity in the manner of a glabella. At 

 the 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 satisfactorily 

 established, 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. Letkaa geogn. i, 123, Tab. IX, Fig. 20. 

 MuRCHis. m. Syst. ii, 664, PI. XXV, Fig. 3. Milne Edw. Crust, iii, 348. 1. Gr. v. 

 Münster, Contrib. 111,47. 1. Goldf. Leonh. and Bronn. Neio Annual, 1843, 542. 1. 

 Trihh.pisif. ScHLOTH. Petr. Suppl. II, 36, 21. 26, 1. Battus pisif. Dalm. Palaad. 57. IV. 1 ; 

 75. V. 1. HisiNG, Leth. Suec. 19, Tab. IV. Figs. 5, 6. Linn, ä Nat. iii, 160, 161. 

 (ed. 12). Bromell, Act. lit. Ups. 1729, 526. 4. e Fig. Wilkens, Verst. 75. Tab. VII, 

 Figs. 38, 39. Modeer, Schrift d. Naturf. Freunde s. Berlin, 14, 248. Tab. II, Figs. 1, 2. 



Locality. — In the alumslate and stinkstone of Andrarum, at the Kinnekulle, etc., and 

 in similar strata in England. 



2. A. IcBvigatus. Dalm. Arsberäth. 1828. 136. Hising. Leth. Suec. 20. 2. Goldf. /. c. 

 542. 2. At the Kinnekulle, near Hönsater. 



3. A. integer. Baltics integer, Beyr. on Bohemian Trilobites, 44, 1, Fig. 19. In the 

 lower Silurian strata of Bohemia. 



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



Remark. — ]My figures of A. pisiformis (Tabic 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 they 

 now certainly appear different, but decidedly more correct, although even now the shades of the 

 furrows may perhaps be rather too deep. The smaller forms (formerly Figs. 5 and 8) do not deviate 

 so materially as to render a particular representation of them necessary, and they have therefore been 

 set aside to make room for other figures of more consequence. 



