228 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Several fragments of the same species, two of which have well-preserved heads, were taken in 
sand or mud at the entrance to Mayaguez Harbor in 12 to 13 fathoms. 
The posterior portion of anotherjspecimen , probably of this species, was taken in the same harbor 
in sticky mud at a depth of 41 fathoms. 
The internal anatomy of this species is closely similar to that of other species of the'genus. A 
very highly developed frontal sense organ lies directly dorsal to the proboscis pore, as was mentioned 
above. This is situated directly between the anterior ends of the cephalic furrows and consists of a 
deep pit lined with specialized epithelium. 
A broad blood lacuna lies in the anterior portion of the head. This divides a little farther back 
into two lateral lacunae beside the rhynchodseum, as usual. Lateral and circum-oesophageal blood 
lacunae as in other species. The dorsal vessel leaves the proboscis sheath a little way behind the 
nephridiopores, and therefore at about two-thirds the distance toward posterior end of oesophageal 
region. 
The proboscis sheath has a very distinct inner longitudinal muscular layer and an outer layer 
of circular muscles. 
The cutis glands are remarkably small and poorly developed. They do not reach one-fourth of 
the distance from the exterior to the circular muscular layer. The outer longitudinal muscular layer 
is much thicker than the two inner muscular layers combined. 
The dorsal ganglia are very voluminous; they are nearly twice the diameter of the ventral. Each 
dorsal ganglion is divided posteriorly into two lobes, of which the upper, smaller lobe ends shortly, 
while the larger, ventral lobe continues directly into the cerebral sense organ. These sense organs 
are very highly developed; the canals communicating with the cephalic furrows pass at first to the 
internal ventral border of the sense organs, and then bend obliquely upward and outward to the lateral 
borders. Later the canal takes a curved course to the internal border again. Posteriorly the sense 
organs end blindly in the broad, lateral blood lacunae. 
The buccal nerves are large and conspicuous. The median dorsal nerve is very small. 
Nephridia . — The nephridial canals are restricted to the middle third of the oesophageal region. 
The main canal on each side lies above the lateral blood lacuna in the angle between the proboscis 
sheath and the oesophagus, while a few branches pass ventrally and lie in contact with the circum- 
oesophageal blood spaces. A single pair of efferent ducts from near the posterior ends of the canals 
pass to the dorso-lateral aspects of the body, as usual. 
Reproductive organs . — The genital products appear to be fully matured in January. The oviducts 
were then partially formed, and extended as rather wide tubes through the two inner muscular layers, 
but failed to penetrate far into the outer longitudinal muscular layer. The position of the oviducts is 
on the dorsal surface of the body and very near the middle line. 
6. Lineus albocinctus Verrill. 
Trans. Connecticut Acad.,x, p.598, pi. i.xx, figs. 1, la, 16, 1900. 
The alcoholic specimen is short and thick-set, with short head, rounded body, and short cephalic 
furrows. Mouth just behind the posterior ends of the furrows. Color yellowish in alcohol, but gives 
no indication as to the original coloration, except that there is a series of narrow, transverse lines 
crossing the posterior portion of the body at fairly regular intervals. Proboscis slender, longer than 
the body when contracted, yellowish in alcohol. 
Length of the contracted specimen 20 mm.; width 2 mm. 
Ensenada Honda, Culebra. A more slender specimen from the same locality shows the trans- 
verse lines more distinctly, is more slender in shape, and has longer cephalic furrows. 
While there remains the possibility that an examination of living individuals of these Porto 
Rican worms would reveal differences which would cause them to be separated from L. albocinctus, 
which Verrill has recently described from Bermuda, yet a comparison of preserved specimens from both 
localities indicates that they are specifically identical. The Bermuda specimens that I have seen were 
preserved in formalin and have retained well their original color, while in the alcoholic specimens 
from Porto Rico the color has almost disappeared. The Porto Rican specimens were considerably 
larger. 
Professor Verrill’s description of the living worms from Bermuda, is as follows: “ Body not very 
long, slender, tapered posteriorly, a little flattened; head usually a little wider than body and more 
