LEODICID^E OF THE WEST INDIAN REGION. 



105 



thirds of their length and then converge to a rounded apex. The first somites are broader 

 than the prostomium, but the maximum width seems to be reached at about the fif- 

 teenth somite. In the living animal the nuchal organs appear as deep hollows revealed 

 by the frequent movements of the peristomial margin; in a specimen which had stood 

 for some days in a laboratory dish these were partly everted, forming rounded lobes, one 

 on either side, each marked by a bright-red median blood-vessel. A similar condition 

 appears in L. Candida (plate 8, figure 8). There are two pairs of thick, conical anal cirri. 



The first parapodium (text-figure 386) has a rounded setal lobe and a very large 

 post-setal one. Between the two is a vertical row of setae, the dorsalmost simple with 

 broad wings, then a number of compound with both basal and terminal portions hooded, 

 and ventral to these other simple ones. I was unable to discover any acicula. On the 

 dorsal surface is a small rounded lobe, in the preserved material covered by an expansion 

 of the body-wall and easily overlooked, into which a few needle aciculae extend. These 

 lobes are shown in text-figures 386 and 387, and evidently represent the rudimentary 

 dorsal cirrus. The tenth parapodium (text-figure 387) is very similar to the first in 

 form. No aciculse could be seen in the normal condition, but in a much flattened speci- 

 men there appeared a tuft of seta-like structures not larger than setse, which terminate 

 just inside the end of the setal lobe. These evidently function as aciculae. A posterior 

 parapodium (text-figure 388) has a more slender posterior lobe and there are two strong 

 aciculse. The one drawn had three hooded simple setae. 



The anterior simple seta (text-figure 389) is long, curved, and covered by a much 

 striated hood. The compound setse (text-figure 390) of the anterior region have long, slen- 

 der terminal joints ending in two large and two or three smaller teeth, the whole terminal 

 joint being covered by a broad hood. A rounded hood-like wing covers the end of the 

 basal portion. In the posterior region of the body the setse are of only one form (text- 



TEXT-FIGURES 386 to 394. Lumbrinereis nuchalis Treadwell. 



386. First parapodium x55. 389. Anterior simple seta x!25. 392. Acicula x410. 



387. Tenth parapodium x55. 390. Anterior compound seta x210. 393. Maxilla x22. 



388. Posterior parapodium x55. 391. Posterior seta x210. 394. Mandible x22. 



