148 CHITONINJE. 



Girdle pretty regularly covered with large narrow, solid, smooth 

 scales. ( Q?r.) 



Length 40, breadth 25 mill., divergence 112. 



Hakodadi, Japan. 



Chiton albrechtii SCHRENCK, Bull. Acad. Imp. Sci. de St. Petersb., 

 v, p. 511 ; Reisen u. Forsch. ini Amur-Lande, ii, Zool., p. 283, t. 13, 

 f. 7-17. Chiton (Lepidop leurus} albrechti E. A. SMITH, Ann. & 

 Mag. Nat. Hist., (4), xvi, p. 115, 1875. Lepidoradsia granofilosus 

 CPE., MS. 



The form collected by H. C. St. John, R. N. at Endermo Harbor, 

 Japan, is larger, (length 65, breadth of central valves 28 mill.), the 

 lirations on the lateral areas are not granulated, and all the valves 

 are distantly concentrically sulcated. 



Subfamily 



Lophyroidea Gpn.,-\-Acanthoidea lophyroidea and Acanthoidea 

 typiea CPU., table of Regular Chitons, 1873, and in Dall, Proc. U. 

 S. Nat. Mus. 1881, p, 284 (1882). Chitonidce and Acanthopleuridce 

 (part) DALL, Catal. Marine Moll. Southeast Coast, Bull. 37, U. S. 

 Nat. Mus., p. 172 (1889.) 



Regular Chitons having the insertion-plates well-developed on all 

 of the valves, and closely grooved or pectinated outside and at edge. 



The retention of Carpenter's groups Lophyroidea and Acanthoidea 

 in anything like the limits given by their author, is simply impos- 

 sible. On the other hand, a perfectly natural group is obtained by 

 uniting these two groups, after excluding the "Acanthoidea isch- 

 noidea" Cpr., and the group CraspedocMton Shutt., which have 

 special characters not yet noticed in print. 



Within the group thus constituted, four genera having well- 

 defined characters are distinguishable, all of them agreeing in the 

 pectinated insertion-plates, though varying in the degree of pectina- 

 tion. 



Synopsis of Genera. 



A. No eyes developed on the valves. 

 a. Girdle scaly. 



Genus XII. CHITON Linne. 



Valves having one or several side-slits in each insertion-plate, and 

 a deticulated sinus separating the sutural plates ; girdle scaly, the 



