THE POLYCHAETOUS ANNELIDS OF PORTO RICO. 
) 99 
a marked increase m width up to the sixteenth. (See fig. 12.) Sixteenth and later segments about 
eight times broader than long. At about the ninetieth each segment becomes longer and narrower. 
Middle of each segment marked by a transverse sharp ridge. Intersegmental constrictions much deeper 
in posterior than in anterior segments. 
Anterior parapodia rather short. Beginning with the second, each has a noticeable posterior lip. 
Farther back, the jiarapodia are nearly twice as long as anteriorly, but with essentially similar form. 
The change is rather abrupt, occurring, in one specimen on the sixth, in the other on seventh segment. 
Distal portion of setae white, as seen with low power, in sharp contrast to darker proximal portion. 
Figs. 42-44 . — Lumbriconereis maculata. Fig. 42, Anterior portion, x 9.5. Fig. 43, Capillary 
seta, x 55. Fig. 44, Uncinate seta, x 110. 
Setae of two kinds. Capillary (see fig. 43) long, curved, with marginal expansion, the whole deli- 
cately striated. Setae of other kind with stout, terminal hook (see fig. 44). The hook with four small 
teeth and with broad lateral expansion, involving the entire seta. Both forms are present in the anterior 
segments. At about segment 35 the second form becomes more prominent, and at segment 42 the 
capillary setie disappear. The others, as seen under low power, have club-shaped ends. 
Color varies from chestnut brown on the posterior segments to light yellow on the anterior. Sur- 
face of body, especially on head and anterior segments, marked with irregular spots of dark brown. 
Neither specimen was complete. The larger, of 112 segments, was 29 mm. long. The head 
was 1 mm. wide. Body, without the parapodia, 
2 mm. at the widest part. 
Collected from Puerto Real. 
Lumbriconereis bilabiata, n. sp. 
Head elongated, like that of L. floridana. 
(See fig. 45. ) First segment longer than second. 
Succeeding segments of uniform breadth, about 
eight times broader than long. Anterior para- 
podia with rather prominent but very narrow 
posterior lip. Farther back a thicker anterior 
lip, nearly as long as the posterior, makes its 
appearance. (See fig. 46 of thirty-sixth parapodium.) The aciculum very strong, black. Sebe had 
nearly all been lost. Those of thirty-sixth segment were as figured. Specimen incomplete, of only 
57 anterior segments. 
Length, 13 mm. Greatest breadth, 1 mm. 
Color, a uniform gray brown. Collected from station 6061. 
ARABELLA (Grube) Ehlers. 
Arabella opalina Verrill. 
Lumbriconereis splendida Leidy, Marine Invert. Fauna of R. I. and N. J., p. 5, 1855. 
Lumbriconereis opalina Verrill, Invert, of Vineyard Sound, Rept. U. S. F. C. for 1872, p. 594, pi. 13, figs. 69, 70, 1874. 
Arabella opalina Verrill, Proc. Ae. Nat. Sci. Pliila., p. 299, 1878. Webster Annelida Chaetopoda of Virginia Coast, p. 242. 
1879; Annelida Cbietopoda of New Jersey, p. 116, 1880; Annelids of Provincetown, Rept. U. S. F. C. 1884, p. 721. 
Annelids from Bermuda, Bull. U. S. Nat. Mus. 1884, p. 321. Andrews, Annelida Pol ych seta of Beaufort, Proo. 
U. S. Nat. Mus., vol. 14, p. 288, 1891. 
Collected from Puerto Real and Arroyo. The specimen from Arroyo had a transverse row of 
brown spots across each segment of the posterior end of body. 
ant 
Figs. 45, 46 . — Lumbriconereis bilabiata. Fig. 45, Head, x 13. 
Fig. 46, Thirty-sixth parapodium; ant., anterior lip; post., 
posterior lip. 
