NATURAL SCIENCES OF PHILADELPHIA. 165 



30. PoLiNA CERViCALis. Corpus gracile, supra salmonea. Caput discretum 

 late rhoraboidale, antice obtusum et emarginatura. Ocelli minuti, in acervoF 

 quatuor confluentes aggregati ; anterioribus elongatis lateralibus ; posterioribup 

 rotundatis sublateralibus. Cervix bene angustata. Long. 3 ; lat. 0*09 poll. 



JIab. In porta " Simoda" Japoniae ; littoralis inter lapides. 



TATSNOSKIA, nov. gen. 



Corpus depressum. Caput subdiscretum. Apertura proboscidis terminaiis 

 cruciata. Ocelli in acervos duos liaeares, antice convergentes ; posteriores 

 usque majores. Maricolae. 



In honorem cl. Tatsnoskii, viri Japonensis eruditi et nobilis. 



31. Tatsnoskia depressa. Corpus depressum, in contractione latum, supra 

 cinnabarinum, lateribus obscurioribus. Caput parvum, obtusum, fronte emargi- 

 nata; apertura proboscidis parva cruciata. Ocelli fusci, minus conspicui, sex 

 in utroque acervo. Long. 1-2 ; lat. 015 poll. 



Hab. In portu " Hakodadi" insulsB " Jesso ;" in fundo arenoso, e 6-10 org. 

 profundo accepta. 



COSMOCEPHALA, nov. gen. 



Corpus depressum, longitudine mediocre, minus contractile. Caput con- 

 tinuum V. subdiscretum, maculis angularibus v. fasciis sepius ornatum. Aper- 

 tura proboscidis in margine frontale inferiore sita. Proboscis laevis. Cervix 

 utrinque pseudorimis inconspicuis (lineis impressis incoloratis) instructus- 

 Ocelli minus conspicui, utplurimum in margine capitis antero-laterali dispositi. 

 Species maricolae, maxima ex parte boreales. 



32. CosMOCEPHALA Beringiana. Corpus sat elongatum, depressiusculura, 

 supra cervinum, subtus pallide aurantiacum. Caput vix subdiscretum, breve, 

 quam corpus angustius, antice rotundatum et eraarginatum, cervinum, maculip 

 angularibus albis in fronte et lateribus ; fascia transversa angusta alba, re- 

 trorsum convcxa, in cervice. Ocelli numerosi, utrinque in acervos duos den?e 

 aggregati. Caput infra pseudorima longitudinali mediana ; pseudorimae cervi- 

 cales inferiores, una transversa utrinque sita, quae in medio vix confluentes. 

 Long. 3 ; lat. 0-2 poll. 



Hab. In freto Beringiano ; e fundo subuloso profunditatis 5 org. 



33. CosMOCEPHALA Japonica. Corpus subelongatum, utrinque obtusum ; 

 lateribus in extentione fere parallelis. Color supra brunnea, subtus alba; caput 

 linea mediana et maculis minutis irregularibus incoloratis ; fronte, et maculis 

 cervicalibus triangularibus, albis. Caput breve subdiscretum, fronte rotun- 

 data, ad aperturam profunde fissa. Cervix utrinque pseudorima obliqua, 

 antrorsum curvata. Ocelli sat magni, in capitis marginibus antero-lateralibus. 

 utrinque 10-15. Long. 4; lat. 0-18 poll. 



Hab. In portu " Simoda ;" littoralis in rupinm fissuris et sub lapidibus. 



Descriptions of two new genera of Shells. 



BY T. A. CONRAD. 



GONIDEA. 



Shell angular, elongated ; hinge furnished with a short, obtuse cardinal 

 tooth, fitting into a corresponding depression in the cardinal plate ; tooth ob- 

 solete in the left valve ; anterior muscular impressions not confluent, lower 

 accessory impressions opposite the middle of the large impression. 



1. Anodon Randalii, Trask. Proceed. Califor. Acad. Nat. Sc. vol. i. p. 28. 



2. A. feminalis, Gould. The anterior muscular impressions have a relative 

 position more nearly resembling that of Triquetra than Unio or Anodon. The 



1857.] 12 



