214 



Long. 8 ; alt. et lat. £ poll. Monterey, in indurated marly clay. 

 Maj. Rich. 



The slender, falcate, and angular form of this shell clearly distin- 

 guishes it from all oilier species. [A specimen in the cabinet of Mr. 

 Cuming, considered as coming from New Zealand, has been described 

 by Philippi under the name of Liihophagus Gruneri. The resem- 

 blance to our shell is very great it' not identical. An error as to the 

 locality maj ha\ e been made.] 



Mvtilus glomerattjs. T. parva, solidula, arcuatim oblongo- 

 ovata, postice obtusa, nitida, ex indico nigrescens; apicibus remotis, 

 excurvatis; valvis ventricosis, oblique subangulatis ; margine liga- 

 mentali recto demum subit6 arcuato; margine ventrali recto \d 

 excurvato; cardinis altera valva dentibus duobus, altera tribus; intus 

 argentata, ad Limbum nigra : cicatricibus profundis. 



Long. | : all. | poll. San Francisco. Maj. Rich. 



A very curious species, clustering on sea-weed in the most crowded 

 manner, so that two adjacenl specimens sometimes wear each other 

 nearly through, from friction in opening and shutting. This circum- 

 stance, with the strong binge and deep cicatrices, show that the speci- 

 mens are mature. The InsMis is coarse, wax yellow. 



Lima tetrica. T. solida, oblique ovato-triangularis, albida, costis 



radiantibus ad is squamis semi-erectis posticis longioribus armatis, 



scens : apicibus acutis, elevatis, remotis, muriculatis ; margin eli 



byssali rectilineari, hiante ; area cardinali lata, valida; fovea* ligamen- 



tali minhne profunda, costa transversali suffulta. 



Long. 1 .', : alt. P: lat. .', poll. Gulf of California, La Paz. Maj. 

 Rich. 



Compared with /.. squamosa, it is narrower and more compressed; 

 the dorsal and ventral margins are less broadly rounded ; the scales 

 are more crowded, twice as long, inflexed at their points, and much 

 more developed ;it the dorsal margin; there are no stria; on the 

 dorsal area. The remarkable brace or rib under the ligament pit, by 

 which a deep cavity at the apex is formed, is remarkable, but possibly 

 accidental. 



Avici i.a STERNA. T. solidula, badia radiis pallidis ornata ; 

 epidermide cinerea serratim fimbriate induta; apicibus ad quad- 

 rantem anteriorem positi>; ala semicirculari, modice obliqua, declivi- 

 tate umbonali tumido, abrupto; cauda longissima, gracili; auriculis 

 magnis, radiatim striatis; fissurS byssali profundissima, acutangulari : 

 margarita argentata, valde* iridescens; limbo fusco-marmorato. 



Long. 2\ : lat. l j ; alt. \ poll. Inhabits Mazatlan. Lieut. Green. 



Has the general appearance of A. semi-sagitta, but the wing is less 

 oblique and curves directly into the cauda without any sinus; the 



