P0LYCH7ETA. 271 



ligule becomes elongate and acuminate,* the dorsal cirrus exceeding it by about one- 

 fifth only ; in the posterior segments the dorsal cirri are upwards of four times the 

 length of the dorsal ligule. Dorsal setae homogomph spinigerous ; superior ventral 

 setae homogomph spinigerous and heterogomph falcigerous ; inferior ventral setae 

 heterogomph spinigerous and heterogomph falcigerous. The shafts of all the setae are 

 striated and all the appendices are strongly fringed (setulose) ; the falciform appendices 

 art' entire at the apex, not bidentate. 



The proboscis was retracted and was dissected out: I., 1; II., 12-12 (oblique 

 acervi) ; TIL, 10 (triangular acervus) ; IV., 15-15 (three unequal rows); V., 0; VI., 

 6-6 (irregular); VII. and VITL, biserial, anterior row large alternating paragnaths ; 

 paragnaths of the posterior row half as large and one and a half times as uumerous 

 as those of the front row. 



Nereis unifasciata, n. sp. Plate IV., tigs. 85 to 88. 



Locality : South-east Cheval Paar. 



A small Nereid (length 11 millims., incomplete behind) characterised by the 

 presence of a dark brown collar across the whole of the dorsum of the second 

 setigerous segment. The buccal and the first setigerous segments are pale brownish 

 at the sides, but there is no band across them. Commencing from the intersegmental 

 groove between the fourth and fifth setigerous segments there are about twelve pairs 

 of small intersegmental brown spots on the back. The feet are equal and resemble 

 those of Ceratonereis pectinifera (p. 272) in the general proportions of parts 

 (Plate IV., figs. 85 and 86). The two worms were collected at the same time and 

 place. 



The distribution of the setae in the foot is as follows : Dorsal, homogomph 

 spinigers ; superior ventral, homogomph spinigers and heterogomph falcigers ; inferior 

 ventral, heterogomph spinigers and falcigers. The heterogomph spinigers are not 

 completely heterogomph, but, at least in the middle and posterior segments, present a 

 condition which might be described as hemigomph (Plate IV, figs. 87 and 88). This 

 small detail affords the only real distinction between the armature of the feet of this 

 species and that of Ceratonereis pectinifera. The proboscis was not extruded, and, 

 although as a rule I do not attempt the description of small Nereids unless the 

 proboscis is extruded, I was anxious to test the specific value of the colour- markings 

 and of the setae. The dissected proboscis showed paragnaths in the adoral division, 

 those of the order VI. in small acervi, of VII. and VIII. in a single row as in Nereis 

 trifasciata, Grube. It is therefore not a Ceratonereis. 



I cannot state any differences between the armature of the proboscis of this species 

 and that of Nereis trifnsci<tt<<.'\ The tact that such a minute detail as the presence 



* The inferior lip of the notopodium is also produced as a ligule, the inferior dorsal ligule, resembling 

 the superior ligule throughout, but rather shorter, 

 t Except that the maxilke show seven teeth. 



