PLATP] IV 

 LARVAL STAGES OF TKILOBITES (Pages 173-170) 



Figure 1. — Aculnspis tubtrculala Conrad. Anaprolaspis ; showing 

 denticulate margin and spines on ccphalon; axis strongly annulated ; 

 eyes sub-marginal. X 20. Lower Ilelderberg, Albany county, New York. 



Figure 2. — The same ; profile, slightly oblique. X 20. 



FiGiRE 3. — Acidaspis tuherculata Conrad. An adult individual, re- 

 stored from fragments and an entire enrolled specimen. Natural size. 

 Lower Helderberg, Albany county, New York. 



Figure 4. — Arges consnngtiineus Clsirke. Dorsal view of a larva at 

 or after the close of the paraprotaspis stage; showing the foi-in and orna- 

 mentation. X 20. Lower Helderberg, Albany county, New York. 



Fkjure 5. — Protlus pai-riusculus Hall. Anaprotaspis; showing 

 strongly annulated axis, with groove at each side; large prominent 

 anterior eyes ; pygidial jilcura indicated by faint grooves, x 45. Ordo- 

 vician, Utica Slate, near Rome, New Yfuk. 



Figure 6. — J^wi'tus pdrciitscuhts Hall. A later moult, near the close 

 of the paraprotaspis stage; showing the larger pygidium which, how- 

 ev(>r, is still incomplete, and the slight backward moveuHMit of the eyes. 

 The right side of the specimen is restored, x 45. Ordovician, Utica 

 Slate, near Rome, New York. 



Figure 7. — ProUtus jmrviusculus Hall. An aduH individual. x2 

 Ordovician, Utica Slate, near Rome, New York. 



Figure 8. — Dahttaniles socialis Barrandi}. (After ilairandi'.) Ana- 

 protaspis stage; showing the large strongly an milated axis; the prom- 

 inent anterior marginal eyes ; mncronate genal angles ; ]>vgidium of 

 three segments. X 30. Ordovician, Bohemia. 



Figure 9. — Dahnnnites socidl is liiivvdude. (After Harrande.) Meta- 

 protaspis stage ; showing the stronger definition of tlie pleuia of the 

 pygidium. X 30. Ordovician, Bohemia. 



Figure 10. — Dabiianiles socialis Barrande. (After Barrande.) Th(> 

 specimen probably represents the close of the paraprotasjiis stage, and 

 shows four segments in the pygidium and the first evidence of the 

 liackward movement of the eyes, which now indent the margin. X 30. 

 Ordovician, Bohemia. 



FiGT'RE 11. — Dnimanitrs anrinlis liarrande. (After P.arrande.) Out- 

 line of an adult individual. X .1. Oi'ddvieian, lioiieniia. 



