398 MA^ATLAN TTNIVALVfiS 



Gi;NUS CHITON, Linn. 



Chiton, pars, auct.—H. Sf A. Ad. Gen. vol. i. p. 474.— Acan- 

 tliopleiu-a, Guild. ; Gray in Proc. Zool. Soc. 1847, p. 67.— 

 Margin spinose : insertion-plates in terminal valve many- 

 lobecl, in middle valves bi-lobed. 



257. CniTOIf FLAVESCENS, H. s. 



Ch. t. ovatd, valde depressa (ad angulam \hQP) Jlavidd, 

 aurantio maculatd ; valvis latis, marginibus suhrotundatis, 

 interstitiis curvatis, valde mtccronatis ; areis lateralihus et jiigo 

 indistinctiorihus ; mun^one parvo, superiore ; totd superfide 

 granulis rugulosis confertim instructa, liaud, punctulatd ; limho 

 2Jallii crasso, suhlcevi, ad margineni spinulis tenuihus, erectis, 

 platiatis histructd ; valvarum lobis, magnis, arcuatis, sinu 

 maximo ; marginibus valvarum intermediarum fissurd duas in 

 lobas divisis, quaruin %ina jJarva, lineis pimctorum utrdque in 

 parte adjugum decurrentibus ; valvarum uUimarum marginibus 

 subacutis, fissuris eirciter x. 



This is the least uncommon of the small Chitons, six speci- 

 mens having been found of it. It is distinguished by its yeUow 

 colour, great depression, and small strong mantle margin, 

 without covering, except at the margin where a ftne row of 

 transparent flattened hairs may be seen. The smaller lobe on 

 the margins of the inner valves is bounded by two rows of 

 holes which proceed to the jugum. Long. "16, lat. "11, aU. "3. 

 Another specimen, roUed into a ball, is larger. 

 Sab. — Mazatlan ; on shells, very rare ; L'pool Col. 



Tablet 906 contains the largest specimen ; another in situ 

 on a broken crevice of Crcpidula ; and 2 separate valves. 



Genus ACANTHOCHITES, Bisso. 



Gray, Proc. Zool. Soc. 1*47, p. 66 : H. Sf A. Ad. Gen. vol. i. 

 p. 482.— Chiton, pars, auct. Mantle with tufts of bristles. 



258. AcANxnocHiTES Aeeagonites, n. s. 



A. t. elongatd, elevatd (ad angulam. WQP), pallido-fuscd, 

 olivaceo et rosea variepictd : valvis inter mediis valde mucronatis, 

 interstitiis a mucronihus valde divergentibxis ; jugo lata, pallida. 



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