28 MARINE INVERTEBRATA OF GRAND MANAN. 



was observed by Mr. Stimpson thus supporting itself in the water for nearly two 

 minutes before it took ground again. Found at low water, under stones, in four 

 f., nullipores, and in thirty f., shelly bottom. 



POSEIDON AFFINIS, Grd., n. s. Body very slender, nearly filiform, about two 

 inches in length when extended and in activity. Color clear reddish above, white 

 below. Two elongated clusters of eyes at the anterior extremity. Mouth under- 

 neath, situated behind the visual clusters. In the laminarian zone. 



NAKED A, Grd., n. g. 



Body elongated, sub-cylindrical. Head obtusely triangular in front; neck slightly 

 contracted ; one pair of rounded ocelli. 



N. SUPERBA, Grd., n. s., Fig. 17. Length from one to two inches ; body poste- 

 riorly attenuated ; head forming an equilateral triangle ; the base of which is at 

 the contracted neck. Color above uniform soft red ; head margined by a narrow 

 band of white. The neck is also marked by a transverse band of white, on which 

 the eyes are situated, far apart. Below white. Dredged in thirty-five f., in the 

 Hake Bay. 



TETRASTEMMA SERPENTINA, Grd., Kell. et Tied., Nordam. Monatsb., ii. 4. Under 

 stones, in the higher levels of the littoral zone. 



OMATOPLEA STIMPSONII, Grd., n. s., Fig. 18. Length usually about six inches, 

 often ten or more. Width in extension one-eighth of an inch ; in contraction often 

 one-half inch. Body sub-compressed, rounded above, and flat below. Head 

 pointed, separated from the body by a slightly contracted neck. Posterior ex- 

 tremity tapering. Eyes six or more, minute, situated in an oblique, simple row, 

 on either side of the head anteriorly. Mouth terminal. Color brown above, with 

 a white margin to the head; a narrow band of white, convex forward, across the 

 middle of the head ; and a sub-triangular, somewhat elongated patch of white on 

 each side, on the posterior part of the head and neck. It is common at low- 

 water mark under stones. 



POLIA OBSCURA, St. Nemertes obscura, Desor., Bost. Journ., vi. 2. Polia gracilis, 

 Grd., K. et T., Nord. Monatsb., ii. 4. Common in the 1st subr., littoral zone. 



GEPHYREA. 



SIPUNCULUS BERNHARDUS, Forbes. Phascolosoma Bernhardus, Pourtales, Proc. 

 Am. Assoc. 1851. Common % the coralline zone, in shells of Dentalium espe- 

 cially. 



