POLYCIRRUS AURANT1ACUS. 193 



shown in Malmgren's figure, the anterior outline below the main fang having a slight 

 convexity about its middle, whilst at its junction with the posterior outline a distinct 

 shoulder occurs. The main fang is large and acute, and the tooth above it is of 

 considerable size, though not so large as in Malmgren's figure. The inferior outline 

 of the base is slightly convex behind the middle, but generally shows an inflection 

 toward the prow. The hooks retain the main features just mentioned posteriorly, 

 though the base is somewhat shorter and a trace of another tooth occurs in some on the 

 crown. 



There are six pairs of nephridia. 



Habits. — This species is not phosphorescent at St. Andrews. 



So far as the description goes this form does not appear to differ from De Quatref ages' 

 Apneumea pdlucida from Brehat. The identification of this widely distributed form by 

 Ssolowiew with the Poly cirrus medusa of Grube cleared up much ambiguity. It is 

 possible that the Ereutho antarctica of Willey ("Southern Cross," 1902), maybe a variety. 



2. Polycibrus aueantiacus, Grube, 1860, char, emend. Plate CXX, fig. 4— ventral aspect 

 of a portion of the body ; Plate CXXVII, figs. 1—1 b— bristles and hooks. 



Specific Characters. — Cephalic lobe with a slight dorsal collar, and when opened 

 forming a frilled margin to the funnel-shaped oral region ; but when folded ventrally 

 it has two lateral flaps with a median fissure as in P. medusa. From the surface of this 

 cephalic plate a dense series of grooved tentacles springs. Body of the typical Terebellid 

 shape, sometimes enlarged dorsally in the region of the anterior scutes or immediately 

 behind them. Length 3 — 4 inches, and with eighty-four to a hundred segments. Of a 

 dull or pale yellow colour, the intestine appearing through the skin as an orange or dull 

 reddish tube; the median tongue-shaped ventral scute is followed by seven to eight pairs 

 closely arranged, then smaller scutes (about twenty) on the longer segments behind. 

 Setigerous processes begin on the second segment and continue to the number of 

 thirty-five to sixty. TJncinigerous processes commence on the ninth bristled segment 

 and continue to the end. Anterior hooks differ but slightly from the posterior. Anus 

 terminal with a crenate margin, and often a prominent ventral papilla, or occasionally 

 a less distinct dorsal papilla. Setigerous processes bifid dorsally, the posterior being 

 the longer division. The margin curves inward ventrally. Bristles in two series, long 

 and short, the former translucent, tapering from the base, with finely attenuate and 

 curved tips devoid of wings, and others with just a trace of wings ; the shorter bare 

 capillary forms much more slender, their tips only projecting beyond the surface. The 

 uncinigerous processes which bear the hooks in a single row on the anterior face of the 

 tip are less prominent than in P. medusa, and continue to the end. Hooks with a 

 long base, a slightly upturned prow, a slight process on the anterior outline below the 

 main fang, a marked indentation above the posterior basal process, and a single tooth 

 above the chief fang. They commence on the sixth or seventh segment. Segmental 

 organs three pairs in one, two and three armed segments after the sixth (Lo Bianco). 

 Tube composed of sand. 



194 



