120 CHiETOPTERITS VARIOPEDATTTS. 



the base. Body large, boldly segmented, and of three regions, as in the family, the 

 anterior region having nine nniramous bristled segments, the fourth segment having 

 powerful bristles in addition to the ordinary forms. Middle region of five segments, 

 with biramous feet, the first segment with great alar lobes, and the last three with fan- 

 like crests. Posterior region with biramous feet, having acerate dorsal bristles and hooks 

 ventrally. 



The genus Chwtopterus was formed by Cuvier for a species from the Antilles. He 

 considered the lamellae of the middle region branchial in function. It was the last genus 

 of his Dorsibranchiates. Cosmovici l holds that it was Dicquemare, and not Cuvier, who 

 first mentioned Ghxtoptenis, but this refers to the animal, not the title. 



1. Chtetopterus variopedatus, Renter, 1848. Plate LXXXIX, fig. 3; Plate Oil, fig. 5 — 

 5j — bristles and hooks ; Plate XCVIII, fig. 7 — tube. 



Specific Characters. — About 4 inches in length, of three regions, the anterior con- 

 sisting of the peristomial funnel and nine bristled segments, the bristles having long shafts, 

 and thin, flattened translucent tips with the outline of a broad spear, the fourth provided 

 with powerful bristles in addition to the ordinary forms, and the last has ventral hooks 

 with eight teeth, whilst the dorsum has a median grooved band. The peristomium bears 

 two long, grooved tentacles with an eye at the outer base of each, some believing that the 

 space between them represents the prostomium. Middle region of five segments, the 

 first with great alar lobes, including bristles, and the last three with fan-like lamellar 

 crests kept in constant motion. With the exception of the first segment of the region, 

 hooks of eleven or twelve teeth occur ventrally. Posterior region of twenty-two or 

 twenty-three bristled segments, each bearing a great dorsal lobe enclosing a series of 

 acerate bristles and swelling into a ventral enlargement bearing hooks with about ten 

 teeth. On the ventral surface are two additional lobes, each bearing hooks with ten or 

 eleven teeth. The body ends in a somewhat lanceolate process on each side and below 

 the level of the anus. 



General colour dull yellow, peristomial cavity brownish (madder) ; first two segments 

 of the middle division with the folded region blackish, and the same tint appears 

 posteriorly in the last three segments. 



Tube elongated, contracted at each end, parchment-like, strengthened with shells, 

 shell-fragments, stones and other structures, and often more than half an inch in diameter. 

 Larva a Mesotrocha. 



Synonyms. 

 1778. Le Boudin de Mer, Dicquemare. Obs. sur la Physique, t. xii, pt. 2, p. 285, pi. ii, figs. 2 and 3. 

 1830. Chsetopterus pergamentaceus, Cuvier. Regne Anim., ed. 2, t. iii, p. 208. 

 1835. „ norvegicus, Sars. Beskriv. og Iagttagelser, p. 54, pi. xi, figs. 29a— 29A. 



1840. „ pergamentaceus, Grube. Actin. Echin. u. Wiirner, p. 69. 



1844. „ norvegicus, CErsted. Nat. Tidsskrift., 2 ser., i, p. 414. 



pergamentaceus, Will. Arch. f. Naturges., Bel. x, p. 328. 

 „ ,, norvegicus, CErsted. Reg. Mar., p. 78. 



i i 



Org. Segment. Annel./ 1880, p. 74, 



