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 MARINE ZOOLOGY V. NEMATODA (?) Nectonema (?). I have seen only one specimen, which was caught when swimming near the surface in Harwich Harbour. It is white, Jijin. long, and about ^V '"■ wide from end to end. When examined with a microscope it is seen to be full of eggs, and is probably a fish parasite which escaped from its host when mature VI. ANNELIDA I. POLYCHAETA Aphrodita aculeata, Linn. Some years ago I often dredged this in the Stour off Harwich, but I have not obtained it there recently. It is much more abundant in the Wallet Lep'idonotus squamatus, Linn. This occurs in most localities, but not in great numbers Nereis diversicolor, Milll. Common in the various estuaries in the mud left dry at low water, and in 1901 was very abundant in the Orwell at Pinmill not much below high-water mark. Some specimens are red, from the amount of h.iemoglobin, others are pale, and some deeply coloured by a peculiar green pigment ■ — cuhrifera, Grube. In 1901 this was com- mon in the sandy mud near low-water off Harwich. It can be distinguished at once from the other species by its peculiar man- ner of swimming — pelagtca, Linn. Before 1 901 this was com- mon, and of large size outside Harwich Harbour, being dredged up with masses of the sandy tubes of Sabellaria spinulosa, but in 1 90 1 this material had been bro'cen up. I found only a few small specimens or none at all. I have also occasionally dredged it in the Aide off Orford — kngissima. In 1901 I obtained from the mud near Pinmill the only specimen of by far the largest Nereis I have ever found irt the south-east of England. It is 7 in. long, and above in. thick, and agrees with specimens collected near Queenborough in the Hete- ronereis collection identified by Dr. E. J. Allen. It was so strong and active that it broke itself in two when put into diluted formalin, which I do not remember to have happened in the case of any other Nereis. On 24 May 1889, when sailing up the Orwell, I saw several specimens of a large Heteronereis swimming near the surface which may have belonged to this species, but none were collected and properly examined — dumerilii, Aud. & M. Edw. Probably com- mon in many places, but often lost out of the dredge. The best specimens I ever obtained were from an old buoy near Pin- mill. When kept alive they soon built a semi-transparent branching tube open at both ends, from which they came out to feed on Ulva latissima, and went back again. One which I had kept alive for a consider- able time laid in a few minutes eggs carefully estimated at about 10,000, and had not I. POLYCHAETA (f«./.) passed into the Heteronereis condition. I never found it completely changed except when swimming near the surface. Though I have lived so long on the estuaries of Suffolk I saw this only on one occasion, which was in the early morning of 16 July 1898, when they were so numerous for a few hours in Harwich Harbour that there were probably something like a million. All those caught appear to be males or females containing no ova. The maximum size was about i in long, which is about one half that of those found at Pinmill, some of which contain ova Nephthys hombergii, Cuvier. I have obtained many from the mud of the Orwell, and it is fairly common in the other estuaries of Suffolk. It varies considerably in colour, being more or less red or brown — caeca, Fabr. I have found a few specimens off Harwich and near Pinmill, but it is ytxy much more rare than the other species Phyllodoce maculata, Mull. Occurs in the sandy mud near low-water level off Harwich, but is comparatively rare Syllis armillaris. Mull. Obtained from material dredged in the Stour off Harwich, and may be common, but often lost on account of its small size. It is interesting from the manner in which it multiplies by the forma- tion of one or more heads in the length of the body and subsequent division Nerine foHosa, Aud. and M. Edw. I have found this in the mud of the Orwell, but it appears to be rare Scolopus armiger, O. F. Muller. All my preserved specimens were collected in Essex, but I think it very probable that I have found it in the sandy mud off Harwich Cirralu/us cirratus. Malm. Though rare elsewhere in the district of the Thames estuary, and I have not found it in any other place in Suffolk, it was most remarkably abundant in 1900 and 1901 in the mudbanks of the Orwell near Pinmill, so that hundreds could be collected in a short time. Though most of them seem to me to be somewhat smaller than they were about 1890, the species has so greatly increased in numbers that it has probably driven away many other animals that at one time were common. Most of the specimens are of dark colour, but others pale. One that I kept alive laid in a short time 91