0\ MOLLUSCA OF THE WEST COAST OF XOKTH AMERICA. 



CiO 



220. 

 221. 

 222. 



223. 



224. 



225. 



226. 

 227. 

 228. 



229. 

 230. 

 231. 

 231 



232. 

 233. 

 234. 

 235, 



Acanthopleura seahrn, live. = CaUfoniiciis, Nutt. Insertion-plates resemble 



Katheriiia. ^'aives with coiir.<e V-shaped ribs, and projectin;.' bealcs. 

 Acanthopleurn Jlu.va . n. s. Green, mottled with orange-red ; not beaked ; with 



only maririnal and diajronal ribs. 

 Ischnochiton Magddlnisis lids. Large, strong-valved, typical. Sculpture much 

 fainter than in soutliern shells. Mantle-margin with striated scales like 

 flattened bristles. Side plates 2- or 3-lobed. Beach-20 fin. Cp. 

 I chnitchiton vercdciUietiii, n. s. Margin similar. Small, arched, sculpture! 

 like Mirfensii, but with 2 rows of bosses, one of which dentates the sulures. 

 10-20 fm. Cp. 

 L(pi(htpl('uru>> rff/ulan's, Cpr. P. Z. S. 1855, p. 232. Subgenus ni Ischnochifon : 

 mant'e-scales Lophyroid, generally striated. Sp. arched, green, shagreened. 

 Side lobes 2-4 : eaves spongy, not projecting. 

 Lepidaph-urus svabrirosfattis, n. s. Small, arched, orange : rows of prominent 

 granules over sliagreened surface. Lobei blunt, slightly rugulose, close to 

 eaves. 8-20 fm. Cp. 

 . L<pi('«pleunifipirfiiiafu<, n. s. Olive: strong sculpture over shagreened jurface: 

 side areas riobed : outer margin ai;d inner sutures pectinated. Bch. Cp. 

 Leiiidopleurus Mirteimi, Midd. lied : highly sculptured over smooth surface : 

 side areas with rows of bosses. Mantle-scales smooth, rounded. 

 , Trachydennon rcfiparosiis, n. s. Sah^erms oi Ischnochitoti : mantle-scales very 

 small, close, smooth. Sp. like scrobiadatus, central pattern in network, 3-6 

 side ribs. 

 Trachi/dennon interstiuctus, Gld. E.E. Centre minutely punctured : C-8 blunt 



side ribs. 

 Trachj/dcnuon frifidus, n. s. Centre-punctures few, deep : 2-4 blunt ribs : side 

 plates with 2 slits. 

 , ITnichi/dertnoH rfr;/^(V'«s, Gld. E.E. No shell known answering to diagnosis and 



figure.] The 4 following species have incisors blunt, eaves not projecting. 

 b. Trachydennon psn(d(identicii!i=^ty\w specimen of dvufietis. False appearance of 

 teeth due to colour or ridges of growth. Closely granular : areas indistinct. 

 Sinus broad, squared : eaves spongy. 

 Trachydennon Got'iicits, n. s. JJlunt parallel riblets along ver^' arched back. 

 Siitural lobes united at sinus : eaves not spongy. 8-20 fm. Cp. 

 . Trachydermon IlattHegii, Cpr. P. Z. S. 1855, p. 231. Large, arched. Insidtj 

 callous, without rows of pimctures to slits : eaves spongy. 

 Tiachyda-mon Xuttallii, Cpr. P. Z. S. 1855, p. 231. Large, plain, flat. Incisors 

 .slightly rugulose : eaves spongy. 

 . Trachydennon iiectens, n. s. Mantle-margin scarcely granular. Rosy, very 

 small, scarcely sculptured: valves beaked and waved as in M. Simpwnii'. 

 eaves and incieoi's uoimal, .. 



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