328 NEREIS LONGISSIMA. 



translucent lobe with four separate frills or lobes at its base ventrally, and it generally 

 lies in front of the bristles pertaining to the former lobe. There the inferior setio-erous 

 process bears the large fan-shaped lamella, often with prominent crenations at its outer 

 border interiorly. In front is the great group of swimming bristles diverging in a fan- 

 like manner at the tip. The ventral lobe is considerably smaller than the dorsal lobe and 

 has a prominent rounded border inferiorly. The lamella to the inner edge of the ventral 

 cirrus is large and fan-shaped, and is joined to a smaller lamella on the outer side of the 

 lobe. From the connate lobes the ventral lamella extends outward but does not reach 

 the tip of the ventral lobe. The connate lamellae thus take the place of a cirrophore, a 

 change which also occurs subsequently in the dorsal cirrus. 



At the hundredth foot the dorsal lamella is large, extending upward nearly as far as 

 the dorsal cirrus, which now projects from the translucent edge of a small process 

 (connate with the dorsal lamella) which bulges externally. The superior lobe of the 

 foot is somewhat less, but retains its elongated triangular outline. The superior 

 setigerous process, its bristles and the long lanceolate lamella beneath, are similar to the 

 sixty-seventh, and so are the parts situated ventrally. The surface of the foot has 

 various specks of black pigment, and in the interior are many ova. 



A considerable change takes place at the two hundredth foot. The lamella internal 

 to the dorsal cirrus is now much less, the cirrus seems to be proportionally longer, and 

 it is less distant from the body and the centre of the foot (by the diminution of the entire 

 organ). The superior lobe beneath it is smaller and of a lanceolate outline. The superior 

 setigerous process has amalgamated with the lamella beneath it and the area of the latter 

 is circumscribed. The inferior setigerous process bears a smaller lamella, still with a 

 crenate border externally and inferiorly. The ventral lamella is tongue-shaped, with a 

 straight upper edge and a curved inferior border. The lamellge at the ventral cirrus are 

 much smaller, but the base of the cirrus is still connected with their border. 



Towards the tip of the tail (Plate LXXIII, fig. 1 d) the lamella to the inner side of 

 the dorsal cirrus has disappeared, a rounded and somewhat thick eminence marking its 

 position. The dorsal cirrus is long. The superior lobe is more opaque, and the seti- 

 gerous lobe and its lamella beneath are narrow and long. The inferior setigerous lobe 

 has only a trace of a thin margin superiorly, and forms a long, narrow, pointed process. 

 The ventral lobe is tongue-shaped, and the ventral cirrus still retains a frilled lamella 

 inferiorly and a small process externally. The black pigment-touches continue to the 

 posterior feet, and so do the ova interiorly. 



An elongated Nereid was dredged in the Bay of Tunis, on the 3rd September, 1870, 

 in the ' Porcupine ' Expedition of that year. In general form and in the absence of 

 paragnathi it resembles a small Eunereis longissima, though its coloration appears to 

 differ. The head agrees with that in Eunereis, but no eyes are visible. Slight elevations 

 devoid of pigment at the sides may indicate them. The tentacles are short, and the 

 tentacular cirri especially short and slender. The fragment of the body is about 4 ins. long 

 in spirit, and from the slight diminution at the posterior end it probably extended an inch 

 or two more. The surface is finely iridescent, and a dull pinkish band (from the intestine) 

 passes along the centre of the dorsum. The first segment (peristomium) is considerably 

 broader than the next. In the structure of the feet this form agrees very closely with 



