102 
I know of no species which could possibly be confused with this 
extraordinary shell, which, from the peculiar triangular cavity be- 
tween the beaks (as in the genus Schizodesma of Gray), may even- 
tually prove the type of at least a subgenus. In the unique speci- 
men before me there is the appearance of ochraceous rays, but I do 
not venture to consider them as characteristic until the comparison 
with further specimens. The shape reminds one of Mulinia Donaci- 
formis. The cardinal tooth is bifid in the left valve. 
MesopgesMA PLANUM. Mes. testd ovato-sublenticulari, transversd, 
valde compressd, inequilaterali, utrdque extremitate rotundatd ; 
sub epidermide corned, albidd, levigatd ; natibus elevatis, acutis ; 
margine ventrali arcuato ; foved ligamentali angustd. Long. $; 
lat. 1 poll. 
Hab. ? 
A peculiarly flat shell, which is not unlike M. complunatum, but 
differs as well in the colouring of its epidermis as in many other. 
particulars. From the little convexity of the dorsal margins, the 
beaks appear extremely angulated. The teeth are obtuse, and the 
lateral short and approximate. 
Note.—The shells described by me in this and the preceding 
papers will be figured in Mr. Wood’s second Supplement to the ‘ Index 
Testaceologicus.’ 
A new species of Chiton, from the Philippine Islands, was exhi- 
bited by Mr. Cuming, which was thus characterized by Mr. G. B. 
Sowerby :— 
CuITon BrrapiatTus. Chi. testd ovali, subelongatd, subdepressd, 
obtuse angulatd ; areis centralibus longitudinaliter minute scabroso- 
sulcatis ; areis lateralibus subelevatis, utringue costis duabus bifidis 
validé irregulariter moniliformibus ; areis terminalibus radiatim 
rugoso-costatis, margine minutissime granuloso; colore pallid? 
fulvo, griseo maculato; margine griseo fasciato. Long. ‘60; 
lat. °35. 
Hab. Dumaguete, Ins. Negros, Philippinarum. H. Cuming legit. 
This species differs from Ch. Janierensis in having the lateral ribs 
bifid and the sculpture generally much more minute. 
