282 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Type. 



Chiton corrugatm Sandberger fr., Verst. Kliein. Scliicht. Nassaii; p. 238, pi. 26, fig, 

 22 a, 185(i, not figs. 22, 22 h, 22 e, 22 (Z =< fish scales and valves of barnacles, as 

 per ty|3ical specimens in Mas. Comp. Zoology, etc. Devonian of Vilmar. 



Cymatochiton Dall. 



Valvis ceiitralibus transversis, antice projectis, satis elevatis, jugo 

 acutiore, lateribus planatis; apopliysibiis modicis, satis extautibus, valde 

 distantibus; sinii jugali latissiino, incurreute; umbonibus extantibus, 

 margine aiitico ad jugiim valde postice siunato. Type (7. Loftusianu& 

 King. 



Tills represents a LeptocMton with the valves thrown forward. It 

 differs from Proholceum in the valves being transverse instead of squared, 

 and in the terminal valves being regular instead of waved. The name 

 Cymatodus used in manuscript for this group by Dr. Carpenter is preoc- 

 cupied by Kewberry (1870). 



Species. 



Cymafochiion Loftusianus King, i.nnals & Mag. Nat. History, I, vol. 14, p. 382 ; Kirkby, 



Proc. Geol. Soc, 18.^0, p. 607, 611, 615, pi. 16, figs. 31-41. Permian, Tunstall 



Hill, England. 

 Cymatochiton Ryclclwltianus Koninc'k Mss. Types Mus. Comp. Zool. Carboniferous of 



Vise, Belgium. 

 ? Cymatochiton tarnaiicola* Eyckholt, 1. c, p. 45, jil. 1, figs. 1,2,3, 1845. Carboniferous 



of Tournay. 

 ? Cymatochiton Scaldeanus * Ryckbolt, 1. c, p. 46, pi. 1, figs. 4, 5, 6, 1845. Same locality. 

 ? Cymatochiton Hoivseanus Kirkby, Quart. Journ. Geol. Soc. 1857, j). 216, pi. 7, figs. 9-13. 



Permian, Tunstall Hill, England. 



This last species is the first undoubted Chiton to put on features com- 

 mon to all the recent forms of the family. 



Until the full record of his investigations is i)ublished, the amount of 

 confusion as to types, discrepancies between figures and specimens, and 

 errors of one kind and another discovered by Dr. Carpenter in his exam- 

 ination of the original types of many of the species can hardly be im- 

 agined. The synonymy is also necessarily left until the complete paper 

 shall be printed. Meanwhile the student is warned that the citations 

 herein actually made are the only ones which are guaranteed to relate 

 to the species named, though there may be, and in most cases are, others 

 which might be cited. The preceding (with synonyms) number all the 

 Palaeozoic chitons actually determined to be such up to 1873. 



In the course of the investigation the following species have been 

 found not to be chitons or chitonoid. They belong variously to fish 

 scales, barnacle {Turrilepas) valves, ostracod Crustacea, and some to un- 

 determined organisms. 



* Doubt attaches to the moUuscan nature of these two minute species, which have 

 Bome crustacean features. 



