95 



Mytilus (Modiolarca) pusillus. T. parva, transversa, sub- 

 cylindrica, ovalis, solida, concentrice striata ; marginibus sub- 

 parallelis ; latere antico truncato, angulo ventrali obtuso ; latere 

 postico late rotundato ; umbonibus tumidis, subterminalibus, con- 

 tortis ; colore cinereo, vel rubro-tincto. Long. -i ; alt. ^ poll. 

 Hab. Terra del Fuego. 



This curious little shell is interesting from its being a repre- 

 sentative from the southern seas of a form not uncommon in 

 northern waters. 



Pecten caurinus. T. trigono-orbicularis, haud crassa, ine- 

 quivalvis, sub-equilateralis ; valva superior convexiuscula, rubra, 

 striis concentricis tenuibus insculpta, costis humilibus rotundatis 

 vel interdum sub-duplicatis ad 20 ornatis : valva inferior convexa, 

 alba, versus marginem rubricans, radiis ad 22 elevatis, quadratis, 

 longitrorsum striatis ; natibus rosaceis compressis ; auribus trans- 

 versis, sub-equalibus, radiatim striatis : intus lactea, rosaceo fim- 

 briata. Long. 2f ; lat. 2^ ; alt, 1 poll. Hab. Port Townsend, 

 Admiralty Inlet, Oregon. 



Of the size and aspect of P. maximus and Magellanicus. The 

 lower valve has the ribs like P. JacobcBus, only they are not 

 furrowed. 



Pecten hericius. T. rotundato-triangularis, equilateralis, 

 equivalvis ; valvis convexis, sub-tumidis : valva superior rosea, 

 lineis exilibus concentricis exasperata, et costis ad 24 angulatis, 

 alternis majoribus et spinis erectis fornicatis insculpta : valva 

 inferior pallidior colore saturation zonata, costis sub-equalibus 

 spiniferis armata ; natibus acutis, prorninentibus ; auribus obli- 

 quis valde inequalibus radiatim squamoso-striatis ; intus porcel- 

 lana ; marginibus crenulatis, rosaceis. Long. 4J ; alt. 1£ ; lat. 4f 

 poll. Hab. Straits of De Fuca, Oregon. 



A very beautiful species, much like P. pallium beneath, but 

 remarkable for the distant ranges of elevated spines on the 

 alternate ribs, the intervening ones being quite depressed, and 

 with merely fine squamous strise, like the rest of the surface. 



Pecten ljetus. T. ovato-triangularis, ventricosa, equivalvis, 

 dilute rosea albo 5-6-radiata: margine ligamentali obliquo, 

 auriculis valde inequalibus, obliquis ; auricula byssica profunde 



