HARDWICKE'S SCIENCE-GOSSIP. 



has the two series of its nerve ganglia fused into a 

 single chord ; the tail is exceedingly mobile and 

 flexible ; there is a huge prqboscis cleft in two at the 

 top, and bearing a fringe of papillce there, and also 

 a little way down ; the feet are large and carry a 

 leaf-like expansion in front of each branch, &c. 

 N. cccca or viargaritacea is a large and brilliantly- 

 coloured sea-worm, the central space adown the back 

 and belly exhibiting a remarkable silvery iridescent 

 play of colour ; the upper lamella of the foot is twice 

 as large as the lobe of the foot itself, while the lower 

 lamella is larger and much broader than the upper 

 one ; the bristles are arranged in two distinct tufts, 

 and do not extend much farther than the edges of the 

 lamellce, they are very slender and pointed, and 

 apparently smooth and simple. N. longisctosa is 

 very similar to the foregoing species, but it is smaller 

 and more common ; the lamelloe are oblong, and 

 some of the bristles are very long indeed, and exceed- 

 ingly flexible ; there are three sorts of these bristles 

 — some are bulged near the middle and minutely 

 denticulated thence to the long sharp point, some are 

 of a similar structure but jointed, while the third 

 kind are very short and of a flat triangular shape, 

 vi^ith the upper flat edge grooved crosswise like a 

 forceps blade, so that the narrow edge seems cut into 

 minute teeth. 



The genus Nereis, although perhaps not the most 

 elaborately formed or marvellously constructed of the 

 marine annelids, is in many respects the most im- 

 portant. The body is always slender, linear, more 

 or less cylindrical, and deeply divided into a large 

 number of segments ; the head is conspicuously and 

 abundantly supplied with antennae or tentacles ; and 

 there is a powerful proboscis armed with strong jaws 

 bearing various shapes of notched teeth ; the feet are 

 exceedingly well developed, protrude freely from the 

 sides, and are amply furnished with branchiae, cirri, 

 and jointed bristles ; the nervous system has very 

 numerous ganglia ; the branchiae are penetrated by 

 the peritoneal fluid, and are without cilia ; the blood- 

 proper is elaborately developed, and is distributed in 

 a plexus embracing the circumference of the conical 

 branchice ; the skin is more vascular than that of any 

 other annelid ; two lateral pouches communicate 

 with the throat, and the wall of the stomach is 

 embraced by a dense tissue of blood-vessels ; the habits 

 are carnivorous. There are som'e twenty-two species 

 of Nereis, of which N. pelagica is perhaps the most 

 common. If you fumble about amongst the loose 

 shingly sand and wave-worn stones on a low-lying 

 shore, you are pretty sure to unearth a lively, wrig- 

 gling, acrobatic worm of a dark -greenish colour, and 

 a not particularly attractive aspect. It may be 

 observed that the distinguishing marks of the various 

 species of Nereis have not been always satisfactorily 

 indicated ; but naturalists usually assign as peculiar 

 features of N. pelagica the following characters — the 

 segment immediately behind the head is about twice 



as long as the following segment ; the branchice lobes 

 are conical and round ; the superior cirrus is twice 

 as long as the pedal lobe to which it is attached ; the 

 proboscis is a very remarkable organ, its orifice being 

 furnished with two curved jaws, the inner edges of 

 which are cut into ten teeth, while below these there 

 are patches of curious darkish horny prickles ; the 

 bristles have a sort of dovetail joint of great flexibility, 

 the end piece of the superior ones is short, curved, 

 and toothed at the edge, that of the inferior ones 

 being slender and prolonged like a fine French 

 Imyonet. N. Dumerilii is distinguished by the post- 

 occipital segment being only very slightly longer 

 than the second one ; the tentacular cirri are nearly 

 three times longer than those of the last species ; the 

 dorsal cirrus considerably overreaches the apex of the 

 foot lobe, and the branchial lobes are short and 

 obtuse though conical and round ; the jaws have 

 about 12 denticles ; there are two brown or yellow 

 spots at the base of the dorsal lobe of every foot ; the 

 bristles are smooth and slender. N.fitcata is gener- 

 ally to be found lodged in some old whelk or spindle 

 shell as the co-tenant and messmate of that marine 

 curiosity known as the hermit crab. It is three or 

 four inches long, of an orange colour, and the tenta- 

 cular cirri are about the same length as the width of 

 the head ; the dorsal lobe of the feet has a strong 

 hump near the base ; the lower cirrus of the foot 

 reaches beyond its lobe ; the jaws show four or five 

 rather shallow notches and a number of minute 

 prickles. N'. renalis differs in some rather important 

 features from the aforesaid species ; the hinder feet 

 are not of the same pattern as the fore feet, for above 

 the base of the upper lobe there is a flat crest ; the 

 branchiae are large, flat, and kidney-shajDed ; there is 

 a curved lobule at the base of the lower cirrus ; there 

 are five denticulations in the jaw ; the bristles are 

 very beautiful, those of the upper feet bearing a 

 sharp fang in the centre, while those of the lower 

 feet present the usual dovetail-joint, the end-piece 

 being broad flat, and serrated very beautifully on the 

 edges. N. longissiina is allied to Phyllodoce, and is 

 rather a lengthy customer of some eighteen inches or 

 more in extent ; the feet are similar to those of the 

 last species, the proboscis has no prickles, and the 

 jaws are very slightly serrated. 



Eitphrosyne foliosa is a curious species, resembling 

 a sea-mouse with shrub-like gills behind the double- 

 branched feet and reaching from one branch to the 

 other ; the bristles are slender and unequally forked 

 at the end. 



Sigalion boa is, in many particulars, an unique and 

 interesting form. It is the only species of its family 

 that is furnished with external^organs of respiration — 

 these consisting of threads beneath the scales ; and it is 

 the only annelid wherein superior cirri and shield-plates 

 exist on the same foot ; these shield-plates are fringed 

 with hairs on the outer edge, and occur on alternate 

 segments as far as the twenty-seventh, whence they 



