A. JS. Verrill — Marine Nernerteans of New England^ etc. 409 

 Tetrastemma dorsale (Abiidgaard) Mclut. 



Planaria dorsalis Abiidgaard, Zool. Danic, vol. iv, p. 25, tab. 142, figs. 1-3, 1806. 

 Tetrastemma fuscum (Ersted, Kroyer's Natiirhist. Tidss., iv, p. 575, 1844. 

 (Erstedia maculata Quatr., Ana. Sci. Nat., ser. Ill, vol. vi, p. 222, pi. viii, fig. 2. 

 Tetrastemma marmoratum Claparede, Beobach. iiber Anat. u. Entwickluiig., etc., p. 



24, pi. v, fig. 14, 1863 (variety). 

 Tetrastemma variegatuvi Johnston, Catalogue Brit. Mus , pp. 20 and 289, 1865. 

 Tetrastemma dorsalis Mcintosh, British Annelids, Part 1, Nernerteans, p. 172. pi. i, 



fig. 4; pi. Ill, fig. 4, 1873; Verrill, Check List, 1879. 

 Tetrastemma dorsale Jensen, Turb. ad Litoria NorvegitTj, p. 81, pi vui, figs. 9 to 12, 



1878. 



Plate xxxiv, figures 13, 14. 



Body only moderately elongated, sub-terete, usually nearly cylin- 

 drical in extension, with both ends obtuse. Head not wider than 

 the body, with two rather indistinct transverse fossa3 on each side. 

 Ocelli forming nearly a square; in full extension more distant longi- 

 tudinally than transversely. Proboscis-pore a little below the end 

 of the snout. Proboscis large, when protruded more than three- 

 foui'ths the length of the body, thickly covered with acute papilloe. 



Color variable ; generally brown or dull reddish, with a well 

 defined light dorsal stripe; or else variegated or mottled with two 

 or more shades of brown, with or without the dorsal stripe. 



Length up to 20"'™; diameter 1-5 to 2""". 



Variations. — Among the variations noted in life, are the follow- 

 ing:— 



Several examples were taken together at stations 310 to 313, off 

 Cape Cod, in 15 to 21 fathoms, 1879. 



In these the general color above was brownish, with a conspicu- 

 ous pale, flesh-colored dorsal stripe, bordered with dark brown on 

 each side ; the brown lateral stripes were freckled with white 

 specks; a pale line crosses the neck behind the eyes; front of the 

 head, margins of the body and tip of the tail pale flesh-color. 

 PI. XXXIV, fig. 13. 



Length 12 to 18"""; diameter 1-5 to 2""". 



Other specimens had the following characters : 



Body slender, 10'""^ long; 1""" broad. Color cinnamon-brown, 

 specked with darker brown, and with a pale median line. Ocelli 

 conspicuous, black. When the head is extended the two pairs are 

 more distant than the space between those of the same pair. Pro- 

 boscis large, more than three-fourths as long as the body, thickly 

 covered with acute, conical papilla?, and protruded from a large 

 pore, which is sub-ventral. Two slight transverse fossae are seen on 

 each side of the head. 



Broad Sound, Casco Bay, July 22, 1873 (No. 72J). 



