62 LEODICIDyE OF THE WEST INDIAN REGION. 



is retained through the greater part of the remainder of the body, though it gradually 

 narrows toward the posterior end. The gills furnish a marked patch of color on somites 

 10 to 22 (plate 5, figure 13). 



The first parapodium (text-figure 201) is not more than half as long as the tenth, 

 with a prominent post-setal lobe, in form much like the dorsal and ventral cirri. The 

 dorsal cirrus is more slender than the ventral and is not so closely joined to the post- 

 setal lobe. Two or three aciculse extend into the setal portion and it carries a dense 

 tuft of setse of the usual three kinds. 



The tenth parapodium (text-figure 202) has a prominent pointed posterior lobe 

 and a rounded anterior one. The dorsal cirrus is slender and extends beyond the setal 

 lobe for one-third of its length. The ventral cirrus has a heavy base, abruptly rounding 

 to a cirrus-like end. Needle aciculse extend into the dorsal cirrus, and two or more 

 aciculse occur in the setal lobe. A later parapodium (text-figure 203), taken between the 

 fortieth and the fiftieth, shows a long, slender dorsal cirrus and a much heavier short, 

 rounded ventral one. This specimen proved to be badly preserved and was somewhat 

 shriveled, so that the proportions in the drawing may not be quite characteristic. There 

 is a pointed posterior lip with a large acicula extending beyond its apex. Ventrally 

 there is a second (hooked) acicula. 



The gills are limited to somites 10 to 22 and are unusual in that instead of beginning 

 and ending with a few filaments, the first and the last have, respectively, 10 and 11. 

 This number is exceeded in the median gills. They are very long and meet over the 

 back (plate 5, figures 13 and 14; text-figure 202). 



The compound setse of the anterior somites are slender, with slender, curved ter- 

 minal portions which are not toothed (text-figure 204). Farther back they are replaced 

 by setse having a similar form, but much longer terminal joints, and in the posterior 

 end of the body the only compound setse are of the form shown in text-figure 205. These 

 have slender basal joints with denticulated hood covering the terminal joints, the latter 

 with terminal and subterminal teeth. In the dorsal part of the seta tuft are very long, 

 slender, simple setse (text-figure 206), while ventral to them are others of about the 

 same length but slightly broadened toward the end. This broadened portion narrows 

 again at the apex of the seta and is very faintly striated along one margin. The pecti- 

 nate setse (text-figure 207) have very few teeth and are not very concave. Some have 

 more teeth than in the one figured, but the number is never great. The dorsal aciculse 

 (text-figure 208) are straight with a simple end and only faintly colored. The ventral 

 aciculse (text-figure 209) are similar to these in general appearance, but are bifid at 

 the end and have a terminal hood. 



None of the published figures of M. belli gives the posterior end of the animal, 

 and only Mclntosh mentions the "slender tail " (1910, p. 449). The Key West specimen 

 lacked the posterior end. Specimens of M. belli from Plymouth, England, showed the 

 posterior dorsal cirri to be very long and slender and one pair of rather short (relative 

 to the dorsal cirri) anal cirri. 



The maxilla is light brown by transmitted light (text-figure 210). The carrier is 

 almost rectangular in form with a dark spot on either side near the distal end. The 

 forceps is slender, its halves noticeably curved. The proximal paired plates are colored 

 like the forceps, with 5 teeth on the left and 7 on the right. The left distal paired plate 

 has 3 large and 3 small teeth and the right has 8. The unpaired plate has 6. There 

 are crescent patches distal to the plates and small plates outside the distal paired. The 

 mandible (text-figure 211) is slender, its inner margins dark brown, its outer margins 

 almost colorless. The beveled portion is delicate and prolonged laterally into a promi- 

 nent tooth-like plate, which is prolonged into a thin chitinous plate not shown in the 

 figure. 



