. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . at Norfolk. There is probably no muddy reachof land that is exposed at low tide from Maine to the Carolinas that is notinhabited by M. jtlicntifln. M. ttttifMi. This is the show shell of the genus Modioln in Americanwaters. It belongs to the Southern fauna, and, like the others of itsgenus, it moors itself towood or other solid ob-jects by means of itsbyssus. It is of aboutthe same size as the lastspecies, but is perfectlysmooth and of a bright-yellowish color, withdark rays o
. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . at Norfolk. There is probably no muddy reachof land that is exposed at low tide from Maine to the Carolinas that is notinhabited by M. jtlicntifln. M. ttttifMi. This is the show shell of the genus Modioln in Americanwaters. It belongs to the Southern fauna, and, like the others of itsgenus, it moors itself towood or other solid ob-jects by means of itsbyssus. It is of aboutthe same size as the lastspecies, but is perfectlysmooth and of a bright-yellowish color, withdark rays over the cen-tral portion. M. recta. A speciesof Mni/iiiln fairly abun-dant on the Pacific coastfromVancouvertosoiith- .v,,,/,,,/,, „„„•„. ern California. It has a long, narrow shell with a dark-brown glossy epidermis; lighter pos-teriorly, and with a short hairy growth. The interior is uhite. Lengththree to four inches. OKI) !•] 1 { PSEUDOL AMELLIBRANCHIATA This third order of lt!iri//>t><l<i is made up of a number of fami-lies in which the gills arc filamentous, but in which Ihr lihmients. >->.; 430 MARINE INVERTEBRATES have become united at their ends to the mantle (on the outer gills)and to the body-mass (on the inner gills). Here also the first tracesof the higher type of gill found in the next order appear; that is, agill in which the filaments are connected by vascular channels in-stead of by cilia. This order therefore is presumed to connectthe true filamentous type of gill with the fully developed lamellartype. As the filaments do not always fuse with the mantle orfoot, the description of the pseudolamellibranch gill becomessomewhat vague, and there is some room for doubt whether thisorder should exist at all. Most of the genera placed in it are monomyarian; that is, theyhave but one adductor muscle, or if two, the anterior one is verysmall and unimportant. The mantle-edges are entirely open,there being no regularly formed siphons. As a rul
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmarinea, bookyear1901
