ACADEMY OF NATURAL SCIENCES. 211 



Genus Acanthochites, Risso? (Leach, 1826). 

 Acanthochites avicula, Cpr. n. s. State Collection, No. 1072. 



A. t. " A. arragonitei " forma magnitudine, pallio, et indole simillima ; sed 

 sculptura et laminis terminalibus diversa ; jugo longitudinaliter sulculis circ. 

 vi. iustructis, interstitiis quasi plauato-squamosis, umbonibus latis ; areis diago- 

 nalibushaud definitis ; lateribus, squamis (quoad magnitudinem) maximis, plan- 

 atis, ovalibus ornatis, seriebus indistinctis divergentibus instructis ; mucrone 

 parvo, antice sito ; colore livido et olivacec-fusco varie tincto ; laminis inserti- 

 ons valv. lat. ut in A. arragonite ; antica, fissuris v. 



Long. 0-16, lat. 0-10. 



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



Genus Acanthopleura, Guilding. 

 Acanthopleura fluxa, Cpr. ?n. s. 



A. t. " A. scabra " simili, sed latiore, pallidiore ; viridi, rubro-aurantio con- 

 spersa ; valvis rectangulatis ; suturis margiDalibus baud conspicuis ; areis 

 diagonalibus satis distinctis ; radiis obtusis fluxis ii., altera diagonali, altera 

 suturali ; tota superficie coDspicue granulosa, granulis acutioribus praesertim 

 albidis ; jugo obtuso,"vix vallato : laminis insertionis ut in A. scabra instructis. 



Long. 0-60, lat. 0-40, div. 110°. 



Hab. Santa Barbara Island, Cooper. 



Foot, in the only dried specimen seen, extremely thin, flat, and narrow. 



Genus Ischnochiton, Gray. 

 Ischnochiton veredentiens, Cpr. u. s. State Collection, No. 518 a (bis), 



I. t. parva, albida, rosaceo tincta ; valvis gothice arcuatis, jugo subacuto ; 

 tota superficie minute granulosa ; areis lateralibus conspicue definitis, minori- 

 bus, costis diagonali et suturali validis instructis, bullis valde expressis munitis ; 

 valv. term, costulis subobsoletis radiantibus ; areis centralibus clathris longi- 

 tudinalibus utroque latere circ. viii. distantibus, expressis, subgranulosis, supra 

 jugum obsoletis; interstitiis a costulis subradiantibus decussatis ; umbonibus 

 conspicuis; marginibus umbonalibus a costis bulliferis valde indentatis, dentibus 

 viii.-x. jugum versus obsoletis, marginibus baud intortis ; mucrone submediano, 

 vix extante ; marginibus lobatis eleganter k clathris pectinatis : intus, sinu 

 maximo, planato, interdum serrato ; laminis insertionis acutis, late unifissatis, 

 valv. term. circ. viii-fissatis, subgrundis conspicuis ; limbo pallii squamis majo- 

 ribus, planatis, tenuibus, vix striatis. 



Long. 0-25, lat. 010, div. 90°. 



Hab. Catalina Island, 20-30 fm., Cooper. 



Subgenus Lepidopleurus, Risso. 

 Isch. squamis magnis, ut in Chitone (Lophyro) instructis, striatis. 



Lepidopleurus pectinatus, Cpr. n. s. State Collection, No. 1073. 

 L. t. " L. Mertensii " simili, sed omnino olivaceo ; areis diagonalibus radiis 



