HETERONEREIS. 163 



with only a minute denticle at its base. Spine one to each branch, 

 very dark brown, with a light base. 



The specimen is 7 inches long, 4 lines in diameter ; and although 

 the last segment has two styles, it is evidently imperfect. The 

 colour is discharged. 



Obs. Has the general form and characters of a Nereis. The ten- 

 tacular cirri are short, about one-half longer than the diameter of 

 the post-occipital segment, which is longer than the second. The 

 terminal pieces of the bristles are smooth. 



(a) Plymouth, Mus. Leach. 



(6) Falmouth. 



2. H. renalis, lobes of the feet conoid, oblique, the dorsal with a 

 flattened crest, and a cirrus crenated underneath and far over- 

 reaching the apex ; lamella of the setigerous branch large and reni- 

 form ; the inferior small and reniform ; inferior cirrus with a curved 

 lobule at its base ; jaws with five denticulations. Length 4". 



Nereis renalis, Johnston in Ann. Nat. Hist. v. 176 (1840). Williams 



in Rep. Brit. Assoc. 1851, 197. f. 14. 

 Heteronereis arctica, Oersted, Grosnl. Annul. Dorsibr. 27. f. 50*, 51, 



60, 65, 68. 70*, and in Kroyer's Naturh. Tids. 1842, 117. Ray 



Soc. Rep. Zool. 1845, 281. 

 Nereis grandifolia, H. Rathke in Nov. Act. Ccesar. Cur, xx. 155 (1843), 



tab. 7. f. 13, 14. Ray Soc. Rep. Zool. 1847, 606. 

 Nereis arctica, Grube, Fam. Annel. 50. 



Hab. The coralline region. 



Desc. Body rather flattish, about 4 inches long, very slightly tapered 

 to the tail, which is obtuse and terminated with two short styles. 

 Head distinct, obtusely triangular, pointed in front with the antennae, 

 which project beyond the palpi. Eyes large, occipital. Proboscis 

 armed with prickles as usual. Jaws chestnut-brown towards the 

 apex, serrated with five denticulations. Tentacular cirri as long as, 

 or longer than, the breadth of the body. Post-occipital segment 

 rather larger than the one behind. Segments about 110, smooth, 

 marked with two or three rugse above the insertions of the feet (No, 

 XXXII.), which are well developed and crowded on the posterior half. 

 Anterior feet normal, with short papillary branchial lobes, of which 

 the dorsal one is the largest and most prominent. The posterior 

 feet are complicated and much unlike the others, for above the base 

 of the superior lobe there is a helmet-shaped compressed crest ; and 

 the superior setigerous tubercle is also furnished with a very large 

 kidney-shaped, veined, leaf-like lamina, under which there is a small 

 oblong lobe ; while the ventral cirrus has appended beneath its base 

 another kidney-shaped leaf-like lamina, and a curved lobule on its 

 upper side. Dorsal cirrus much longer than its lobe ; that of the 

 middle feet crenated on the under side : ventral cirrus rather long. 

 Bristles slender, forming considerable brushes on the middle and 

 posterior feet. Spines dark brown. 



M 2 



