THE POLYCHiETOUS ANNELIDS OF PORTO RICO. 
193 
Family NEREIDS. 
NEREIS Cuvier. 
Nereis bairdii Webster. 
Nereis bairdii Webster, Annelids from Bermuda, Bull. No. 25, U. S. Nat. Mus., (>. 312, pi. 8, figs. 22-28. 
There are apparently two-well marked varieties in this species, differing in color and in form of 
parapodia. One with outer portion of head and dorsal surface of anterior segments brown. A row of 
cc lorless spots in this band on head and across anterior end of first six or seven segments. Parapodia, 
especially the posterior ones, with excessive development of dorsal ramus, as described by W ebster. A 
rectangular white patch on dorsal surface of each pair of segments, overlapping the line between the 
two, though lying mainly in posterior one. The second variety has a band of brown around the head, 
much narrower than the first and with no white spots. A transverse brown band on each segment, 
much darker near posterior edge. Lobes of parapodium much blunter and more rounded than in first 
variety and posterior parapodia not with excessive development of dorsal ramus. Dorsal cirri much 
longer than in first variety. Webster figures long compound setae with smooth terminal joint. In the 
Porto Rico specimens this terminal joint is finely toothed. These specimens agree so closely with one 
another, and with Webster’s description of the species, in so many anatomical features, that I have 
thought it best to regard them as color varieties of the same species. 
Collected from Puerto Real, Arroyo, Boqueron Bay, Mayaguez, Porto Rico, stations 6065, 6091, 
6092, 6062, and 6063; Ensenada Honda, Culebra. 
Nereis mirabilis Kinberg. 
Nereis mirabilis Kinberg, Annulata Nova, Oefvers. af. K. Vet. Akad. Forh. 1864, No. 16, page 571. Quoted from Ehlers, 
Annelids of the Blake, p. 117, pi. 37, figs. 1-6. 
Nereis gracilis W ebster, Annelids from Bermuda, p. 313. 
From a careful comparison of Ehlers’ s with Webster’s description I conclude that these are 
identical species. Ehlers figures the antennse as entire, while Webster figures them with rather long 
basal joints. The single specimen at my disposal (from Boqueron Bay) has a short basal joint, easily 
overlooked in preserved material. 
Nereis arroyensis, n. sp. 
Head broader than long, the dorsal surface shading off gradually into the palps, with no sharp 
line between the two. Anterior edge rounded, with two thick antennae. Eyes four, anterior pair 
semilunar in form (with transparent “lens”?) (fig. 30). The posterior dorsal tentacular cirri had 
been lost; the other cirri short (fig. 30). In other specimens than the one figured these cirri were 
longer. Body colorless, broadest in 
front, tapering gradually to posterior 
end. Body of 73 segments. Two 
very long anal cirri. 45 mm. long, 
2.5 mm. wide. 
Parapodium with dorsal cirrus 
longer than ramus ( fig. 31 ) . Ramus 
of two lingulae, the dorsal a little 
longer than the ventral. Setae of 
dorsal ramus compound, with long 
basal joint with prominent trans- 
verse striations. Terminal joint 
long, nearly straight, finely toothed. 
Dorsal setae of ventral ramus like 
setae of dorsal ramus. Ventral setae with basal joint like dorsal, terminal joint short, hooked at end 
and with a row of long delicate spines on side. Dorsal lingula of ventral ramus with anterior and 
posterior lobe (“lip”), the anterior a little the larger. Ventral cirrus not quite so long as dorsal. 
Toward posterior end, parapodia much as anteriorly, except that lobes become a little more pointed, 
and the setse with long terminal joint become relatively much more numerous in the ventral ramus. 
The number of setse in the dorsal ramus becomes very small. 
Collected from Arroyo and station 6052. 
2d— F. C. B. 1900—13 
Figs. 30, 31 . — Nereis arroyensis. Fig. 30, Head, x 17. Fig. 31, Parapo- 
dium, x 18. 
