MAZATLAN UNIVALVES 193 
The serrations of the margin in the only perfect specimen 
found are distinctly visible through the dried cuticle, as they 
are also in some dead valves in other respects agreeing with 
the shell. Below the large scales of the mantle margin appears 
a row of gill-like flattened hairs, as in the young of L. articu- 
latus and albolineatus. Long. ‘17, lat. °*12, alt. 04. 
Hab.—Mazatlan ; 1 sp. off Spondylus calcifer ; L’pool Col. 
Tablet 897 contains the specimen. 
Genus ?TONICIA, Gray. 
Proc. Zool. Sec. 1847, p. 65.—H. & A. Ad. Gen. vol. i. p. 473.— 
Chiton, pars. auct. Plates of msertion as in Lophyrus: mantle 
smooth. 
951. ? Tontcta ForBEsIt, 2. s. 
? Tt. ovata, subelevata (ad angulam 115°) brunned, olivaceo 
varie picta ; valvis intermediis mucronatis, sulcis in gugo Y=for- 
mibus a mucronibus projicientibus decurrentibus ; lineis diagon- 
alibus valde tuberculatis ; areis lateralibus sparsim punctatis, 
ad valvarum inierstitia tuberculato-corrugatis ; areis centrali- 
bus rugis curvatis divergentibus, ta valvis terminalibus circiter 
Xill. ; mucrone conspicuo ; limbo pallit sublevi, tenwiori ; 
valvarum lobis intus declivibus, sinu alto, lato ; gugo intus roseo ; 
margimibus valvarum et sinus dense serratis, fissuris in valvis 
intermedtis und in latere utroque, in valvis terminalibus rugis 
externis convententibus. 
Two specimens were found of this very beautiful species, 
which is dedicated to the memory of the learned and deeply 
lam@nted Prof. E. Forbes, whose promised assistance, had he 
lived, might have prevented many errors in the present work. 
Neither of the specimens shew any trace of imbricated scales, 
though they may possibly exist. The structure of the marginal 
plates closely resembles that of Lophyrus albolineatus. Lozg. 
78, lat. °45, alt. °14. 
Hab—Mazatlan ; extremely rare; Z’pool Col. 
Tablet 898 contains the finest specimen; the other is in 
Mr. Darbishire’s cabinet. 
April 1856. s 
