58 LEODICID^ OF THE WEST INDIAN REGION. 



on somite 27 with a single filament on the left side and two filaments on the right. The 

 largest number of filaments that I could determine was fi >e. They continue to practically 

 the extreme posterior end of the body, only ten somites in one specimen being free from 

 them. Since the last somites are always very small and much crowded together, this is 

 practically at the end of the body. The number of filaments decreases posteriorly, but 

 they remain bifid to within thirty somites from the end. The gills are slender (plate 5, 

 figures 1 and 3) and may meet over the dorsal surface of the body. A great part of the 

 general appearance of the animal is due to their color. 



The first parapodium (text-figure 184) has a lanceolate dorsal cirrus and an elongate 

 oval ventral one. The setal portion is rather large relatively to the cirri and carries a 

 cirrus-like posterior lip. There is a single acicula. The tenth parapodium (text-figure 

 185) has a dorsal cirrus much like that of the first, while the ventral cirrus is thick and 

 fleshy and is carried on the end of a ventral pad-like swelling. The setal portion is large 

 and has an asymmetrical posterior lip, its apex directed upward. There are four or 

 five dark aciculae. In the one-hundredth parapodium (text-figure 186) the dorsal cirrus 

 is very small, arising at the base of the gill, and the ventral cirrus is much smaller than 

 anteriorly, though retaining in a general way its form. The setal portion is conical, with 

 the posterior lip forming the apex of the cone and with dorsal and ventral aciculse. I 

 could find no needle aciculse in the dorsal cirrus in any appendage. In the parapodium 

 drawn there was a minutely denticulated ventral acicula (text-figure 187), but I could not 

 find it in other parapodia; there is evidently variation in this particular. The appear- 

 ance of the dorsal aciculse varies considerably, some being almost colorless and others, 

 corresponding in position to these in other somites, being a very dark brown. 



The maxilla (text-figure 188) has a very short carrier with small wings, the basal 

 portion of the forceps short and thick, the terminal halves not very much tapered, all 

 very dark. The proximal plates have 4 prominent teeth on either side and are dark along 

 their edges but lighter farther back. The distal paired plates have 6 teeth on the right 

 and 3 on the left, while the unpaired has 5. All of these plates are dark-colored. 

 There are two crescent-shaped pigment patches, the larger being on the right; also a 

 small light-colored pigment patch lateral to either paired plate, and a dark one lying 

 median to the unpaired. The mandible (text-figure 189) is rather small, its shafts nearly 

 of uniform width, light brown externally, but very dark on the median line, the beveled 

 portion very dark except for a central brown line and with a white "wing" extending 

 anteriorly from each half. On the median edge each wing has a light-brown patch. 

 This mandible is quite characteristic and affords an easy method of distinguishing this 

 species from the variety brevibranchiata. 



The compound seta (text-figure 190) has a basal joint only slightly widened at the 

 end and obscurely striated, with a long slender terminal joint. A marginal serrated 

 wing appeared in most cases, though it was not possible to demonstrate it in all. The 

 pectinate setse (text-figure 191) are characterized by the large number of teeth and by 

 the long terminal teeth which may bend around so as to be in contact. These setse 

 are not evident in the anterior somites, but become larger and with much longer stalks 

 posteriorly. The simple setaj are long and slender, curved toward the apex, and some- 

 times with a narrow wing along the convex edge (text-figure 192). 



The dorsal aciculse (text-figure 193) are straight, with bluntly rounded ends. There 

 is much variation in color, some being nearly colorless and others very dark. The one 

 figured was light-colored for a very short distance; throughout the middle it was very 

 dark, lightening again at the base. 



M. acicularum was first described by Webster from specimens collected in Bermuda 

 by G. Brown Goode. I found it very common in Bermuda between tides on muddy 

 flats, such as occur in the upper end of Flatts Inlet or in Fairyland Creek. Some were 



