18 LEODICID^ OF THE WEST INDIAN REGION. 



to a segment and with olive-brown irregular markings on each side. Antennae pale, 

 banded with flake white." Those of my collections (plate 1, figures 5 and 6) had brown- 

 ish-green markings in front of the eyes on the prostomium, with similar pigmentation 

 on either side of the median line throughout the anterior region of the body. These 

 lateral patches are joined by intersegmental narrow bands of the same color, most 

 easily seen when the animal is expanded. Anteriorly there are prominent median dor- 

 sal white areas of considerable size which are continued posteriorly by a median row of 

 white spots. The color of the posterior region of the body is dependent on the character 

 of the intestinal wall or its contents, on the blood, and on the sex products. Sometimes 

 (as in figure 7, plate 1) it may be brown from the intestine, or (as in figure 5) greenish 

 blue from the sex products. A small speck of greenish-brown pigment occurs on the 

 ventral face of the prostomium, but otherwise the ventral surface is uncolored except 

 that posteriorly it has a double row of large black spots. On the dorsal face of each 

 parapodium throughout the posterior half of the body is a small black spot (plate 1, 

 figure 5). The tentacles showed the flake-white spots described by Verrill. 



Preserved material is a dingy gray color with a marked iridescence. 



The form of the prostomium varies with the degree of expansion. The specific name 

 unifrons indicates that there is no central fissure dividing the prostomium, and at times 

 the anterior margin does seem to be entire; at other times a very faint depression ap- 

 pears, this being the more usual condition. When expanded the prostomium is broader 

 than long (plate 1, figure 6) with prominent eyes. The median tentacle extends to about 

 the fourth somite, the paired ones decreasing in size from the inner to the outer. They 

 are all articulated, though this shows best in preserved material, the articulations in 

 life being obscured by the pigmentation. The peristomium at its anterior edge is about 

 as wide as the prostomium, but widens toward its posterior end. It is about twice as 

 long as the second somite. Later somites increase slightly in width to about the middle 

 of the body, while posterior to this is a gradual decrease in width. The nuchal cirri 

 are about as long as the prostomium and very slender. Verrill stated that they are artic- 

 ulated, but I was unable to verify this point. The dorsal cirri are rather stout, larger 

 than gill-filaments in gill-bearing somites. There are two pairs of anal cirri (plate 1, 

 figure 8), one pair much longer than the other and very slender. 



The gill arrangement is usually as described by Verrill. One individual had the 

 gills beginning as a single filament on the third setigerous somite; there were two fila- 

 ments on the fifth, three on the ninth, and four on the twelfth. Later somites showed 

 variable numbers, the largest number being six on somites 21, 22, 26, and 27. Somites 

 28 to 34 had five filaments, 35 to 38 four, 39 and 40 three, 41 to 43 two, and 44 one. 

 They disappeared entirely at the fiftieth setigerous somite. The gills are rather prom- 

 inent in the anterior region, meeting across the mid-dorsal line of the body. The main 

 stem is rather small (text-figure 21) and the filaments about equal in length. 



The first parapodium (text-figure 22) has a rounded post-setal lobe and two aciculsB. 

 The cirri are both prominent, the dorsal more so than the ventral. The dorsal has a 

 brown pigment patch on its dorsal surface and a tuft of needle setse. The tenth para- 

 podium (text-figure 21) has a setal lobe with its median portion drawn out into a dorso- 

 posterior and an antero-ventral lobe. The dorsal cirrus is very long and slender, while 

 the ventral one is small and conical, carried on a globular swelling. The dorsal cirrus 

 is carried rather high on the parapodium and has needle aciculse at its base. There are 

 two large aciculaj in the setal lobe. Posterior parapodia (text-figure 23) have a pointed 

 post-setal lip, while the cirri have about the same relative size that they have in anterior 

 somites, the ventral one, however, having lost its globular base and become slender. 

 There is a small needle acicula in the dorsal cirrus and a large ventral acicula in the 

 setal portion. 



