a THE NAUTILUS. 



Tanicella Carpenter, Bull. Essex Inst. V, p. 154, 1873 (Chiton 



marmoreus Fabricius). 

 Boreochiton G. O. Sars, Moll. Reg. Arct. Norv., p. 116, 1878 



{Chiton ruber L., and C. marmoreus Fabrieiua). 

 Toniciella Thiele, Gebisa d. Schneeken, II, p. 389, 1891 {T. 



mannorea Fabr.). 



Section Cyanoplax Pilsbry. 



CyaTwplax Pilsbry, Man. XIV, pp. 40, 44, 1892 {Chiton hart- 

 wegii Carpenter) . 



Subgenus Spongioradsia Pilsbry. 



Spo-ngioradsia Pilsbry, Man. XV, p. 65, 1894 {Trachyradsia 

 aleutica Dall). 



In view of the similarity of names the following synonymy 

 may be useful : 



Genua Lepidopleurus Risso. 



Lepidopleurus (Leach Ms.) Risso. Hist. Nat. Eur. Merid. IV, 

 p. 267, 1826 (1st sp. L. cayetanus (Poli) Risso) ; G. 0. 

 Sars, Moll. Reg. Arct. Norv., p. 110, 1878. 



Section Leptochiton Gray. 



Leptochiton Gray, P. Z. S., 1847, p. 127 {Chiton cinereus Mon- 

 tagu (not Linne) == C. asellus Spengler) ; Carpenter, 

 Suppl. Rep. Brit. Assoc., pp. 530, 612, 650, 1864 (1st sp. 

 mentioned as a real member of the genus is Leptochiton 

 nexiis Carpenter). 



? Lepidochitoii Carpenter, Rep. Brit. Assoc., pp. 317, 349, 

 1857 (1st sp. C. lividus Midd.). Includes also C. msrteri- 

 sU Midd., C. scrohwulatiis Midd., and C. proprius Reeve ; 

 the latter = C. dispar Cpr., not Sowerby. 



I confess to an inability to get anjiihing like systematic 

 order out of Middendorff's extraordinary tangle of names, 

 except where some subsequent author has fixed a species as 

 type, as in the case of 8ymm£trogephyrus (Midd., Feb. 1848), 

 which Chenu (Man., p. 383) has declared to be typified by 



