48 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 1342] 
ing a simple gill both on the upper and lower sides of the lateral append- 
ages. The other, R. Americanus, (Plate X, figs. 45, 46,) has gills that 
are more or less branched on the upper side of the appendages, as shown 
in fig. 46, but none on the lower side; the appendages are also longer, 
especially posteriorly, and differently shaped. The proboscis is remarka- 
bly long and large, and when full y protruded itshows four large, black, 
sharp, fang-like jaws or hooks. Both these worms are destitute of true 
blood-vessels, such as most of the allied worms possess, but have the 
general cavity of the body filled, between the various organs, with 
bright red blood, which shows through the skin, giving a more or less 
red or purple color to the whole body and proboscis. 
The two species of Lumbriconereis already referred to (p. 320,) occur in 
similar localities, aud are usually associated with the two preceding spe- 
cies, but they are less rapid burrowers and require for their safety lo- 
calities where the sand is compact and mixed more or less with mnd, 
or where it is somewhat sheltered from the force of the waves. In 
sandy coves, and especially on the flats of sandy mud, close to low- 
water mark, the smaller species, L. tenuis, is generally very abundant, 
penetrating the sand, beneath the surface, iu every direction. It is 
often a foot or more in length when extended, and not much larger than 
coarse thread or small twine, and bright red in color. When the sand 
in these localities is turned up with a spade, their drawn-out, red, thread- 
like bodies can usually be seen in large numbers, but they are so fragile 
that it is difficult to obtain an entire specimen. The head is obtusely 
conical, a little fattened, smooth, pale red, and iridescent, without eyes. 
The other species, L. opalina V., (Plate XLII, fig. 69,) is much larger, grow- 
ing to the length of eighteen inches or more, and about .10 to .12 of an 
inch in diameter. Its color is dark bronze, or reddish brown, or pale 
red, the surface reflecting the most brilliant opal-like colors. It is 
easily distinguished from the ZL. tenuis by its four eyes in a row across 
the back part of the head. Both these species, when removed from 
their burrows, coil themselves in a long spiral. They burrow readily 
and deeply, but not so rapidly as many other worms, and do not seem 
to have permanent tubes. Another worm, found in similar places and 
readily mistaken for LZ. tenuis on account of its long, slender, almost 
thread-like body and red color, is the Notomastus filiformis V.; but 
in this species the head is very acute, the lateral appendages and 
sete are very different, and the color is paler red, with bands or rings 
of bright red. This species has, moreover, a smooth, subglobular pro- 
boscis, without jaws, while the former has a powerful set of compli- 
cated jaws, without a distinct proboscis, and they are widely different in 
internal anatomy. The latter feeds upon the organic matter coutained 
in the mud that it swallows, while the species of Lumbriconereis are 
carnivorous, feeding upon other worms, &c. A second and much larger 
species of Notomastus occurs in similar places, though apparently pre- 
ferring a greater proportion of mud. This species, N. luridus V., grows 
