28 



It was found in exposed situations. — G. B. S. 



Chiton Frembleii. Chit, testd oblotigci, complanatd, olivaceo- 



yiiscd, lineis albido-viridibus varid ; valvcB anticce radiis elevatis 



subgranosis ; inter mediarimi marginibus angulosis, areis lateralibus 



hiradiatis, radiis subgranosis, interstitiis longitudinaliter subsul- 



cutis ; limbo seiis brevibus Jrequentibus obsito : longA^ylat. ] poll. 



Hub. in Sinu Valparaiso. 



This species differs from Chit, setiger, King, in being much flatter, 

 in the more angular margins of its intermediate valves, and in its 

 more numerous and much shorter bristles. 



It was found only on one exposed rock covered by a small species 

 of Fucus. — W. J. B. 



****** Ligamento marginis piloso. 



Chiton scabriculus. Chit, testa ovali, planiusculd, cinered, 

 aibido-variegatd ; valvd anticd, areis lateralibus valvarum inter- 

 mediarum et parte posticd valvce posticcB radiulini scabroso- 

 lineatis ; valvis intermediis et parte anticd valvce posticce longi- 

 tudinaliter sulcatis ; limbo piloso, cinereo, rtifo-articulato : long. 

 1|-, lat. i^ poll. 



Hab. ad littora Americas Centralis. (Guacomayo and Puerto 

 Portrero.) 



Found under stones. — G. B. S. 



******* Ligamento marginis fasciculato-piloso. 



Chiton retusus. Chit, testd oblongd, postice retusd, pallescente ; 

 valva anticd, areis lateralibus valvarum intermcdiarum et valves 

 posticce area posticd turgidis, radiato-sulcatis ; areis centralibus 

 valvarum intermediaruyn et area anticd valvce posticce sulcato- 

 asperis ; ligamento marginis Jasciculis pilorum nwiimis plurimis : 

 long. l-rVj lat. -/-jy poll. 



Hab. ad oras Americae Centralis. (Guacomayo and Puerto Por- 

 trero.) — G. B. S. 



Genus Placunanomia. 



Testa adhserens, subaequivalvis, irregularis, complanata, marginera 

 versus plicata, interne vitrea. Cardo internus, dentibus duobus 

 elongatis, crassis, subcurvis, divaricatis, basi convergentibus in 

 valva inferiore, sulcis duobus ligamentiferis in superiore. Valva 

 inferior cardinem versus superficialiter irregulariter externe fissu- 

 rata, organo adliaesionis subosseo inter testae laminas inserto et 

 externe fissuram implente. Impressio muscularis in utraque valva 

 subcentralis. In valva superiore organi adhsesionis impressio super- 

 addita. 



This interesting genus partakes of the characters of the genera 

 Ostrea, Plicatula, Placuna, and Anomia. It may be regarded as 

 the connecting link between the two latter. With an arrangement 

 of the hinge approaching very nearly to that oi Placuna, it has the 

 distinguishing organization of Anomia, while the external appear- 

 ance of the shell, especially if viewed in situ, bears the strongest 

 resemblance to a Plicatula or some of the plicated Oysters. The 

 organ of adhesion, which in its bony character (for it is more bony 



