212 PROCEEDINGS OF THE CALIFORNIA 



plerumque iv. dense tuberculiferis, radioque altero suturali tuberculis inflexis, 

 margines valvarum pectinantibus ; costis transversis crebris validis ; costulis 

 longitudinalibus acutis distantibus superantibus, quarura margines suturas anti- 

 cas pectinant ; valv. term, ut in areis diag. • sculptis, seriebus tuberculorum 

 creberrimis ; tota superficie minutissime tuberculata : intus, valvis centralibus 

 unifissatis, terminalibus xi.-xv.-fissatis : scabs pallii irregularibus, confertis, 

 minutissime longitudinaliter striatis. 



Long. 0-85, lat. 0-50, div. 110°. 



Variat : interdum aurantio nebulosa. 



Hab. Catalina Island, Santa Barbara Island, beach, Cooper. 



Lepidoplenrus scabricostatus, Cpr. n. s. State Collection, No. 1071 c. 



L. t. parva, aurantia, elevata ; valvis gothice arcuatis, jugo acuto ; tota 

 superficie conspicue et creberrime grauulata : areis lateralibus majoribus, con- 

 spicue definitis ; seriebus granulorum majorum iii. radiantibus, subobsoletis ; 

 umbonibus baud conspicuis ; marginibr.s umbonalibus colore iutensiore pseudo- 

 dentatis, parum intortis ; areis centralibus seriebus costularum angustarum sub- 

 obsoletarum longitudinalibus, valde distantibus, granulis majoribus instructis ; 

 valv. term., costulis granulosis similibus radiantibus ; mucrone vix mediano, 

 parum conspicuo : intus, lobis suturalibus separatis, sinu maximo, planato ; 

 laminis insertionis lat. unifissatis, term, x.-xii.-fissatis, subobtusis ; subgrundis 

 modicis, subconspicuis : limbo pallii latiore, squamis imbricatis, elongatis, 

 transversim striatis, crebris ornata. 



Long. 0-30 ; lat. 0-17 ; div. 100°. 



Hab. Catalina Island ; 10-20 fm., Cooper. 



Subgenus Trachydermon,* Cpr. 

 Ischnocbiton : squamis pallii minimis, confertis. 



Trachydermon Gothicus, Cpr. n. s. State Collection, 518a. 



Tr. t. parva valde elevata, viridi, rosaceo et olivaceo eleganter tincta ; valvis 

 gothice arcuatis, jugo acuto ; areis lateralibus parvis, arcuatim distincte definitis, 

 granulosis ; umbonibus prominentibus ; marginibus umbonalibus colore tessel- 

 latis, intortis ; areis centralibus longitudinaliter costatis, costis rotundatis, cre- 

 bris, haud valde expressis, interstitiis parvis, vix interdum decussatis ; valv. term, 

 ut in ar. lat. sculptis, posticS mucrone mediano, subelevato : intus, lobis sutur- 

 alibus haud separatis, medio latissime sinuatis ; laminis insertionis, lat. unifissatis, 

 term, viii.-x.-fissatis, obtusis, subgrundis haud elevatis : limbo pallii minutis- 

 sime squamuloso, granulis confertissimis, subrotundatis, lsevibus ; circa mar- 

 ginem pilulis suberectis. 



Long. 0-20, lat. 010 ; div. 80°. 



Hab. Catalina Island, 8-20 fm., Cooper. 



Genus Leptochiton, Gray. 

 Leptochiton nexus, Cpr. n. s. State Collection, 1071a. 

 L. t. parva, albocinerea, valvice gothis arcuatis ; areis lateralibus vix defini- 



* From the Greek for rough skin. 



