LEODICID.E OP THE WEST INDIAN REGION. 31 



mark off a prominent lower lip. The second somite is about equal to the third in length, 

 but not more than one-quarter as long as the first. The nuchal cirri are slender and 

 colorless and extend to the anterior border of the first somite. The dorsal cirri are all 

 colorless and rather inconspicuous and there is a single pair of anal cirri which are colorless 

 except for faint yellow bands (plate 3, figure 8) . 



The gills are very prominent throughout the anterior region of the body, and show 

 very great variation in their structure. They begin on somite 6 or 7 with 1 filament; 

 in later somites other filaments are added (plate 3, figure 7), but the number of these 

 filaments, so far as I can judge from Webster's description and my own observations, is 

 very variable and depends on the size of the animal. The largest number in Webster's 

 specimens was 4 on somites 16 to 37. In a Bermuda specimen I found 6 on somite 23. 

 One Tortugas specimen had 4 to 7 filaments on somites 17 to 38, while another and 

 larger individual had 10 to 14 on somites 13 to 37. Behind this region there is a 

 reduction in number in all individuals, but the gills continue to the posterior end. 

 Bifid filaments are not uncommon. 



The first parapodium (text-figure 66) has a short presetal and a longer postsetal lobe 

 and a relatively prominent dorsal cirrus, seven or eight times as long as the setal lobe. 

 The ventral cirrus has an oval outline, is about twice as long as the setal portion, and is 

 attached for nearly the entire length of the latter. In life the brownish pigment extends 

 on to the dorsal surface of the parapodium, but in alcoholic material only two brown 

 patches remain. There are two aciculse in the setal portion and a tuft of needle aciculse 

 in the base of the dorsal cirrus. The tenth parapodium (text-figure 67) shows a much 

 larger setal lobe than did the first, but the anterior and posterior lips are essentially of 

 the same form. The dorsal and ventral cirri are smaller than in the first parapodium, 

 the latter being nearly triangular in form and carried on the end of a swollen base. The 

 gill is attached at the base of the dorsal cirrus and has a large main stem from which 

 the filaments arise. This figure was drawn from a large specimen, with a large number 

 of gill-filaments. In most cases there would not be as many as nine of these on the 

 tenth parapodium. There are two large aciculse in the setal portion, and a tuft of needle 

 setae in the base of the dorsal cirrus. 



Behind the twenty-seventh somite a ventral acicula is added to the parapodia, and 

 the pad on the ventral cirrus disappears at about the fifty-second. The seventieth 

 parapodium (text-figure 68) is very much smaller than either of the other two figured, 

 and while the setal lobe is not so very different in form there is a noticeable decrease in 

 the size of the cirri and the gills are much more slender. The figure was drawn from a 

 large specimen; in smaller ones there would be only one filament. I was unable to find 

 any needle aciculse in the posterior somites. The twentieth parapodium from the 

 posterior end (text-figure 69) has lost the distinction between the setal lobes and the 

 gill is very small and to be distinguished from the cirrus only by the central blood-vessel 

 in the gill. The ventral cirrus is short and thick. 



The simple set83 are of two kinds, one (text-figure 70) noticeably curved to an acute 

 point and striated along one or both edges. The others are not so much curved, and their 

 central portion is thicker, with a minutely striated keel along both margins (text-figure 

 71). It is probable that these represent extremes of variation of the same form of seta. 



The compound setse (text-figure 72) have a rather stout base, which is widened and 

 truncated at the apex, the terminal joint of each being rather short and provided with 

 an apical and a subapical tooth, the whole covered with a striated hood. The pectinate 

 setae (text-figure 73) have from 12 to 15 teeth, the terminal one at one end being longer 

 than at the other. These forms of setse occur throughout the body, but in the median 

 region the shafts are longer and the number of setae greater. The dorsal aciculae have 

 simply rounded ends, but the ventral ones (text-figure 74) have bifid ends covered with a 



