350 KEPOET OF^ieMMISSIONER OF FISH AND FISHERIES. 



the sand aside, making the burrow larger, and furnish points of resist- 

 ance toward which the parts behind can be drawn, or against which 

 the head and anterior parts can push in continuing the burrow. 

 The head, moreover, is extremely'changeable in form, at one time 

 being spear-shaped, with a pointed tip and thin edges, and con- 

 stricted at the neck; in the next minute broadly rounded; then 

 perhaps truncate or even deeply emarginate at the end ; then gradually 

 losing its distinctness and blending its outlines continuously with 

 those of the body; or perhaps shrinking down to a small oval' form, 

 not more than one-third as wide as the body just back of it. All these 

 and many other changes can often be witnessed within a very few min- 

 utes, and are so effected as greatly to aid the creature in burrowiug 

 This worm can also leave the bottom and swim rapidly in the water, 

 the body being usually kept up edgewise and impelled forward by the 

 undulatious of the body, which thus become horizontal. When swim- 

 ming in this way the motion reminds one of the swimming of a snake 

 or an eel. In addition to the terminal pore, for the proboscis, there 

 is a deep lateral slit or fossa on each side of the head, aud a large ven- 

 tral orifice beueath. Tlie latter is ver^^ changeable in form, changing 

 from elliptical, long oval, oblong, or hour glass-shape, to circular in rapid 

 succession. There are no eyes. Along each side of the greater part or 

 the length of the body, the voluminous, transversely-banded lateral 

 organs can -be imperfectly distinguished through the translucent integ- 

 ument, as well as the median cavity, in which a dark pulsating tube can 

 sometimes be seen. The lateral organs commence at about the anterior 

 fourth in small specimens, but in the larger ones relatively nearer the 

 head, for in the largest they originate only six or eight inches back of 

 it. The portion in front of the lateral organs is thicker and more cy- 

 lindrical than the rest of the body. 



The color of the largest specimens is generally light red or flesh-color, 

 with the lateral edges and central band translucent grayish white, the 

 lateral organs showing through as dull yellowish transverse branches, 

 with diverticula between them ; head yellowish. But one large speci- 

 men was dull brownish yellow ; others are yellowish white, with the 

 lateral organs deep chestnut-brown, crossed by white lines. The small 

 specimens are generally paler, usually pale flesh-color or yellowish 

 white and often milk-white. Some of the diversity in color may be 

 due to sexual differences. This species has also been dredged on sandy 

 and shelly bottoms in six to eight fathoms in the sounds. 



Dr. Leidy has also described another similar species, from Great Egg 

 Harbor, under the name of MecheUa lactea, which I have not been able 

 to distinguish, unless it be what I have regarded as the light-colored 

 young of if. ingens ; the white color seems to have been the principal 

 character by which it was distinguished from the latter. 



The Meclcelia rosea is, however, a very distinct species, but it lives in 

 similar places and is often associated with the M. ingens. It has very sim- 



