NEREIS DUMBRILII. 309 



bristles, a head with four eyes, two frontal tentacles or papillae, and rudimentary palpi. 

 The proboscis is unarmed, and the rectum is differentiated. Two short anal cirri are 

 present. He noted for some days the development of the parts and the increase of the 

 segments to sixteen. He found that the armature of the proboscis appeared when there 

 were eight or nine bristled segments. He describes the bristles of the early stages as 

 embryonal, the tip being short with three spikes on the edge. 



At St. Peter Port, Guernsey, in July, 1868, a female of the ordinary outline, and 

 measuring about 2 in. in length, was laden as far forward as the fifth foot with large 

 ova. These ova are larger than in the Heteronereid forms ; indeed, about six or seven 

 made up the diameter of the body. The eyes are of average size, and no change is 

 apparent in the structure of the feet or bristles. This is an example of that condition in 

 which the sexual elements are developed without external change. 



A large female, again, of the ordinary type presents slightly enlarged eyes, but no 

 change in the feet. The body-cavity is filled with small ova. Another procured in 

 Birturbury Bay, Ireland, in June, is in the same condition, along with what appeared to 

 be an epitokous female, since no papillee occurred on the dorsal cirrus, but the specimen 

 was so badly preserved that doubt remains. A few stray ova are seen, but their nature 

 is doubtful. 



Habits. — It is a less active species than Nereis pelagica, yet swims easily through the 

 water in an undulating manner, without coiling the long tentacles. It rapidly secretes 

 tubes even in a collecting bottle, and when deprived of them often enters those of 

 Terebellge or other forms. When in its own tubes in sea-water an undulating motion of 

 the body is kept up, apparently for purposes of respiration, as in Phijllodoce and other 

 annelids. The tubes in nature are tough, the mucus being strengthened by fragments of 

 seaweeds and debris, and they are generally attached to Fuci and Laminariaa, as CErsted 

 originally found, though occasionally to other structures. It is somewhat brittle : even 

 withdrawal from its tube suffices to cause fractures of the posterior region, and the same 

 happens when placed in spirit. In the separated fragments the dorsal blood-vessel 

 remains distended, and irregular contractions take place for some time. 



At St. Peter Port, Guernsey, the tubes are sometimes stiffened by fragments of 

 shells, both univalve and bivalve, Foraminifera, minute fragments of gneiss, particles of 

 gravel, and fragments of Algse and mud. At Lochmaddy, in the Outer Hebrides, besides 

 the tough secretion and mud, the tubes are frequently strengthened and tufted with Algse, 

 and here and there a fragment of shell. Broad-leaved Algge are often bound together by 

 the secretions in Bressay Sound, besides tufts of filamentous Algas, and the walls have 

 many fragments of shells and occasionally fragments of Fuci. The tubes of some from 

 Valentia Harbour, again, are hairy all over with filamentous Alga3. At Herm the tube 

 of a small example with Algge and fragments of Trochus attached was neatly placed inside 

 the rim of a small Hallo tis between tide-marks. An example has the palps soldered in 

 the middle line, whilst the frontal tentacles are absent. Another from Norway shows 

 the reproduction of a tail. 



The Lycoris cirrkosa of Risso * (1826) appears to be allied to Nereis Darner Mi, with 

 long tentacles and tentacular cirri, and may be that form. 



1 < Hist. Nat. Europ./ t. iv, p. 417. 



