230 STKEBLOSPIO SHRUBSOLII. 



the coast of New Jersey. He and Benedict 1 also described this and a new form in 1884. 

 It is doubtful, however, if the second form pertains to the same genus as the first. 



1. Streblospio Shrubsolii, Buchanan, 1890. — Plate LXXXIX, fig. 7 ; Plate CIV, fig. 10 



hook. 



Specific characters. — Snout forming a bluntly-conical process bearing four eyes. At 

 its base are a pair of ciliated tentacles, whilst from the dorsum of the first segment are 

 the longer branchiaB. Body minute, 6 — 1 mm. in length, of thirty to forty-eight segments, 

 nearly cylindrical, only tapering a little toward the somewhat blunt posterior end. Little 

 differentiation into anterior and posterior regions except as regards bristles. It terminates 

 posteriorly in a truncated extremity on which is the anus. Feet indicated only by small 

 lamelte behind the bristle-bundles, the dorsal being a little above the bristles and the 

 ventral a little below them. Bristles winged and capillary anteriorly, and the same forms 

 occur dorsally throughout. Ventrally the winged hooks commence on the eighth segment, 

 but capillary forms accompany them in diminishing numbers to the posterior end. Two 

 green nephridia anteriorly. An inhabitant of mud. 



Synonym. 



1890. Hekaterobranchus Shrubsolii, F. Buchanan. Quart. Journ. Micr. Sci., vol. xxxi, n.s., pp. 175 — 200, 



pis. xxi and xxii. 



Habitat. — In soft mud usually covered by about an inch of water at Sheppey, and 

 extending so far up as Gravesend on the south side of the river Thames. It is associated 

 with Haplobranchus, Nais, Hemitvbifex, nematodes, and planarians (Florence Buchanan). 



The head (Plate LXXXIX, fig. 7) resembles that of a Spionid, for it is bluntly conical 

 and bears four eyes, the two posterior wider apart. Occasionally additional eye-specks 

 occur. A pair of crenated ciliated " tentacles" (Buchanan) arise from the base of the prosto- 

 mium, the ridges carrying the cilia, the effect being heightened by the yellowish-green 

 transverse streaks. They are hollow, for a process of the ccelom enters them, and also 

 a contractile blood-vessel. They are bent forward in search of food, the minute particles 

 of which ( e. g. Infusoria) are carried by the cilia to the mouth, which is on the ventral 

 surface of the peristomium. 



On the dorsum of the peristomial segment is a pair of branchise, which are longer 

 than the tentacles, and of a reddish-orange colour, mainly due to a vascular loop. They 

 have shorter cilia than the tentacles, and at the base of each is a tuft of three short 

 capillary bristles, whilst a little behind and beneath is the ventral tuft with a lamella 

 below it. The body of the first segment reaches further forward ventrally than dorsally, 

 and thus makes a kind of collar (Buchanan). So far as can be judged from Miss 

 Buchanan's description and figures it is possible that the bristled segment is the first 

 body-segment, the peristomium being in front of it. The body is from 6 — 10 mm. in 

 length, nearly cylindrical throughout the greater part of its length, and only tapered a 

 little toward the tail, which is by no means attenuate. In section it has a slightly 

 flattened curve dorsally and ventrally in the " thoracic " region, the lateral outline is 

 1 'Rep. Fish and Fisheries U.S.A./ pp. 728—729, pi. v, figs. 60—64, and pi. vi, figs. 65—72, 1881. 



