Polychcetous Annelids from Florida, Porto Rico, Bermuda, etc. 26o 



right. Distal paired plates with 7 on the right and 4 on the left. The 

 unpaired plate with 8 (plate 3, fig. 1) teeth. The mandibles had very long, 

 slender, dark shafts, the beveled portion being small and its surface white, 

 except for a black outer edge (plate 3, fig. 2). 



Collected July 1915 at Mangrove Key, Key West Harbor; Boca Grande; 

 and at Marquesas, in sandy mud within digging distance of low-water mark. 



Type in American Museum of Natural History. 



Marphysa nobilis n. sp. 



A large species, one specimen of average size measuring, after preservation, 

 350 mm. in length, with a peristomial diameter of 4 mm. The three somites 

 following the prostomium were of the same breadth as the prostomium, but 

 there was a later gradual enlargement to 7 mm. at the seventeenth somite. 

 Behind this there was a gradual narrowing to the posterior end, this narrowing 

 being more evident from somite 17 to somite 30. These measurements were 

 taken on preserved material in which the relative proportions may not have 

 been exactly as in life. 



The body of the living animal is a flesh color due to the contained blood, 

 and anteriorly is markedly iridescent. The only pigmentation of the surface 

 is in the form of green bands on the otherwise colorless tentacles and numerous 

 yellowish spots scattered over the anterior surface of the body. The posterior 

 part of the body during life is decidedly transparent. Preserved material is 

 uniformly brownish gray. In life, the red gills give a decided tint to the 

 middle portion of the body. 



The prostomium (plate 3, fig. 3) is bilobed, though the depth of the median 

 depression varies at different times during life. When fully expanded its 

 anterior edge is nearly straight and it tapers on either side to a narrower base. 

 The tentacles are longer than the prostomium, approximately equal in size, and 

 only very gradually tapering to the apex. The green color noticeable in living 

 material is lost on preservation, and it is then seen that a constriction occurs 

 at each green band ; this resembles an articulation, but I think is not a true 

 jointing. There is one pair of small eyes. 



The peristomium is rather short, though its absolute size naturally varies 

 with the degree of expansion. The constriction between it and the second 

 somite is very obscure, so that the two are practically continuous. 



The gills begin as a single filament on the region of the twenty-fourth to 

 the twenty-ninth somite and acquire a second filament a few somites behind 

 this. They later have as many as 6 filaments (plate 3, fig. 4) and when fully 

 developed meet from opposite sides across the dorsal surface. Posteriorly 

 they become smaller and finally disappear entirely at about 45 somites from 

 the posterior end. 



The first parapodium (plate 3, fig. 5) with prominent dorsal and ventral 

 cirri and a long, cirrus-shaped, posterior lobe. The anterior lobe is truncated. 

 Two short, very black aciculae are in this parapodium and it carries dorsally a 

 single tuft of needle setae. The ventral seta tuft is short and lies behind the 

 ventral cirrus and contains compound and pectinate setae. The tenth para- 

 podium has a large posterior lobe with the apex bent dorsally and a truncated 

 anterior lobe. The ventral cirrus is conical, the dorsal with a decided lobe 

 on its ventral surface. Three aciculae extend beyond the end of the para- 

 podium. Parapodium 150 (plate 3, fig. 4) shows much less distinction be- 

 tween anterior and posterior margins than do the anterior ones. The ventral 

 cirrus is small, borne on a rounded base, the dorsal cirrus also small with a 

 ventral lobe. The gill is rather thick and heavy at the base, but soon divides 

 into filaments. The setae are as in anterior somites and there are two aciculae. 



