342 REPOll^ll^COMMISSIONER OF FISH AlsB FISHERIES. 



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ing a simple gill both on tlie upper and lower sides of the lateral append- 

 ages. The other, R. Americanus, (Plate X, iigs. 45, 40,) has gills that 

 are more or less branched on the upper side of the appendages, as shown 

 in fig. 46, bnt 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 it shows 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 Lumhriconereis already referred to (p. 320,) occur in 

 similar localities, and 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 mud, 

 or where it is somewhat sheltered from the force of the waves. In 

 sand}- 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, in 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 flattened, smooth, pale red, and iridescent, without eyes. 

 The other species, L. opalina V., (Plate XIII, fig. 09,) 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 L. tenuis hj 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. The}" burrow readily 

 and deepl}', 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 L. tenuis on account of its long, slender, almost 

 thread-like body and red color, is the Ifotomastus filiformis Y. ; but 

 in this species the head is very acute, the lateral appendages and 

 sette 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 Avidely different in 

 internal anatomy. The latter feeds upon the organic matter contained 

 in the mud that it swallows, while the species of Liwibriconereis are 

 carnivorous, feeding upon other worms, &c. A second and much larger 

 species of Notomastiis occurs in similar places, though apparently pre- 

 ferring a greater proportion of mud. This species, N. luridiis V., grows 



