i-< HNO in i 

 (/nth!,-n.< ( lABPl WTEH v. Sci. 



p, 648; Proc, Cal, &cad 8ri. ill, p. 212, 



An unusual character in ihi> II, prettil' 



ci.- is that the sutural hmiin.-e iitly con; 



jiiLral sinus] ly a layer liniiiL r tin- very bl 



'Indt'nfn'H* [ dtntient <lld.| a false Mppeanmn- 0j 



given t.. the saturee by the spot* of darker painting. (<) j / s 



I-( II.\M III I - 



I. RETiPORoeus Carpenter, UnfiguretiL 



Shell small, subelongate, ashen colored ; mucln-lfvatcd, u 

 arcuate. Vulvi's sulxjuadratc, apices conct-alcd. lateral areas litil.- 

 defined, having '> to (>' i-oun<lc(l, obsolete riblcts, here an.l thm- with 

 acute projecting granules. Central areas pitted all over. ; 

 small, punctate. Terminal valves with more acute close nai 

 riMrts. Mucro little raised, anterior. Inside with hroad -utural 

 sinus. Insertion plates of intermediate valves with one slit on each 

 side, terminal valves with about 12 slits. Girdle bearing dote, 

 minute scales, which are little elongated. 



Length 11, breadth 7 mill.; div. 90. 



v 



Trachydermon retiporosus CPU., Brit. Asso. Rep. 1863, p. 

 Ischnochitoii (Trachydermon} retiporosus CPR., Proc. Aead. 

 Sei. 1'hila. 1865, p. 59. 



A species like scrobiculatus ]\Iidd., the central pattern in net- 

 work, lateral areas with 3 to 6 ribs. 



Known to me only by Carpenter's description. 



I. FLECTENS Carpenter. Unfigured. 



Shell small, subelongate, roseate; jugum acute: lateral areas 

 scarcely defined. Valve margins excurved, sum IT incurved, a] 

 very prominent; valves having minute, not very c 'Miles 



sparsely suhradiatinir, all over very minutely punctulate. Mucro 

 conspicuous, anterior. Inside: sutural sinus wide, Hat: 

 seaivelv projecting. Terminal valves with 11. median 1 slit. 

 Girdle very minutely granulate. 



Length 8f, breadth 6 mill.: div. 110. (Cpr.) 



* 



