CHITON. 149 



scales rounded and solid, closely imbricating, rarely separated. 

 Type C. tuberculatus Linne. 



aa. Girdle with short bristles. 



Genus XIII. EUDOXOCHITON Shuttleworth. 



Valves having several side-slits in each insertion-plate, the 

 sutural-plates continuous across the sinus, which is represented by a 

 mere wave; girdle leathery, beset with short, stiff bristles. Type C. 

 nobilis Gray. 



AA. Eyes developed on end valves and lateral areas. 

 a. Girdle leathery, nude or nearly so. 



Genus XIV. TONICIA Gray. 



Valves having pectinated insertion-plates ; sutural-plates separated 

 by a squared denticulate sinus; eyes developed in more or less 

 regular rays on forward part of lateral areas and on end valves. 

 Girdle leathery, naked or with a few hairs. Type C. elegans 

 Frembly. 



aa. Girdle covered with spines or spinelets. 



Genus XV. ACANTHOPLEURA Guilding. 



Valves having pectinated insertion-plates with one or several side- 

 slits, the teeth in the posterior valve directed forward instead of out- 

 ward ; sinus denticulate or smooth ; eyes small, scattered among the 

 granules of the surface. Girdle bearing long calcareous spines, or 

 closely clothed with short ones. Type C. spinosus Brug. 



Genus CHITON Linne, 1758. 



Chiton L. Syst. Nat. edit, x, p. 667 (first recognizable species C. 

 tuberculatus) ; edit, xii, p. 1006. SPENGLER Skrivter af Naturhist. 

 Selsk., 1797 (first species C. tuberculatus). LAMARCK, Prodr. 

 Anim. s. Vert., p. 90, 1799 (sole example cited, C. tuberculatus). 

 WOOD, Gen. Conch, and Index Test. (C. tuberculatus the first 

 species). GUILDING, Zool. Journ. v, p. 27, (example, C. squamosus 

 SowB.=fre&ercM/afaa). GRAY, P. Z. S. 1847, p. 65, 66. SHUTTLW., 

 Bern. Mittheil. iv, p. 72. CARPENTER & DALL, Proc. U. S. Nat. 

 Mus. i, p. 300 (1878), type C. tuberculatus. Not Chiton H. & A. 

 AD., Gen. Rec. Moll, i, p. 474 (1858.) 



Lophyrus (in part) POLI, Test. utr. Sicil. i, multivalvia, p. 2, 4, etc. 

 H. & A. ADAMS, Gen. Rec. Moll, i, p. 469 (in part.) 



