Fam. 7. Nephthydidae.—The elongated body is quadrangular in section, the dorsal and ventral surfaces being almost flat. (For head see p. [262], and for parapodium, p. [264].) The two lobes of the parapodium are widely separated, and each is fringed with a membrane, while a sickle-shaped "gill" hangs down from the under surface of the notopodium. The pharynx is enormous. Of the genus Nephthys two species, called the "Lurg" or "White Cat" by fishermen, occur on our coasts. Their active movements and beautiful mother-of-pearl tint are characteristic. N. hombergii Aud. and Edw. occurs on the shore, and down to 20 fathoms; it is 3 or 4 inches long, and may be found burrowing in the sand; the chaetae exceed in length those of N. caeca Fabricius, which occurs less frequently and in deeper water, and is larger than the preceding. Both are Atlantic forms.
Fam. 8. Amphinomidae.—The body in this family is either vermiform, as in Eurythoe, or oval and flattened, as in Euphrosyne and Spinther. The head carries a peculiar sense organ, the "caruncle," consisting of a smooth axis with the sides folded so as to look like a number of lamellae. The parapodia carry gills. Most of the Amphinomids are tropical and Southern forms.
Eurythoe borealis Oerst. measuring 6 inches, occurs all round the British area, from the Shetlands, where it occurs in deep water, to the Channel Isles, where it lives on shore, under stones, etc. (For parapodium of Amphinome see p. [264].)
Euphrosyne.—The body is short, oval, and flattened. The parapodia are not distinct processes, but the chaetae extend from each side of each segment nearly to the middle dorsal line, and are absent ventrally (Fig. 137, C, p. [265]). The dorsal and ventral cirri are more or less filiform, and there is an intermediate similar process on the back (? = lip of chaetigerous sac). Amongst the chaetae are a number of curious branched processes—usually called "gills."[[380]] The presence of these and of the chaetae give the upper surface of the body a fluffy appearance. E. foliosa Aud. and Edw. is fairly common under stones on our southern shores. It is about an inch in length and is of a cinnamon-red colour.
Fam. 9. Eunicidae.—The elongated body is provided with parapodial gills in more or fewer segments (except in Lumbriconereis). The "gills" may be cirriform (Hyalinoecia), pectinate (Eunice, Onuphis), or more complex (Diopatra). The notopodium is represented by a lobe (usually called "cirrus") into which an aciculum projects; in some cases it even contains a few chaetae; most of the neuropodial chaetae are jointed (Fig. 138, F). The prostomial tentacles vary in number; they may be three or five, or five and two short "frontal palps," or they may be absent. Peristomial cirri are absent, though in Eunice, Diopatra, and Onuphis "nuchal cirri" are present on the dorsal surface of the second segment (Fig. 134, D). One of the most characteristic features in the anatomy of the Eunicids is the peculiar jaw apparatus (see p. [270]). The majority of the genera form permanent tubes of parchment-like consistency, which may be further strengthened by the addition of grains of sand, small pebbles, etc.; the tubes may be branched.
Eunice has five tentacles, two great palps, and a pair of nuchal cirri; the gills are pectinate, and there are four anal cirri. E. harassii Aud. and Edw. is about 8 inches long. It is reddish-brown, with white spots down the back, one to each segment, and others at the sides. The gills begin at the sixth segment, and when fully developed have eleven branches. The dorsal cirrus is not longer than the gill. E. philocorallia Buch.[[381]] forms its tube amongst the branches of Lophohelia prolifera, in 200 fathoms, off the west coast of Ireland.
Marphysa resembles Eunice, but has no nuchal cirri. M. sanguinea Mont. is a fine bronze colour, with bright red gills, which commence on the twentieth segment, and have only four or five branches. The worm, which measures 12 to 18 inches, and is as thick as one's finger, hides in clefts in rocks and under stones below low water. Mediterranean. It is known as "Rockworm" in the Channel Islands.
Hyalinoecia Mgrn., in addition to the five prostomial tentacles and palps, possesses a pair of small "frontal palps" arising from the anterior border of the prostomium; there are no nuchal cirri, and the gills are simple filiform processes. H. tubicola Müll., about 3 inches long, is yellowish-brown, and forms a transparent, parchment-like tube. Atlantic and Mediterranean.
Fig. 170.—Ophryotrocha puerilis Clap., Metsch. × 25. ci, Bands of cilia; cp, ciliated pit (nuchal organ); J, jaws. (From Korschelt.)