HETERONEREIS. 



IG5 



Length 



of the ventral cirrus ; superior cirrus overreaching its lobe. 

 18". 



Nereis longissima, Johnston in Ann. Nat. Hist. v. 178. 



Heteronereis paradoxa, Oersted, Gi-oenl. Annul. Dorsibr. 23. f. 50, 63, 



64 & 66; Kroyer's Naturh. Tids. 1842, 116. 

 Nereis paradoxa, Grube, Fam. Annel. 50. 



Hab. Coast of Ireland. 



Desc. The specimen before me is of the extraordinary length of 

 2 feet ! but as it has become very soft in the spirits, it would perhaps 

 not much exceed 18 inches when alive. It is of the thickness 

 of a goose-quill, and of a pearl colour with olivaceous feet, which are 

 very large and flexile. Head distinct, rather small, obtusely trian- 

 gular ; the antennae minute and shorter than the palpi. Proboscis 



• No. XXXIII. — Heteronereis longissima. 



N.B. The numbers affixed to the Woodcut figures express the number of 

 the segment from which the foot was taken that served for the figure ; 

 m means that the foot was from near the middle ; and p, from near 

 the posterior extremity of the body. 



large, destitute of all horny prickles, but armed with powerful jaws, 

 which are only faintly serrulated near the base. Post- occipital seg- 

 ment not larger than the second. Tentacular cirri short, not so long 

 as the breadth of the segment. Segments very numerous. Feet 

 (No. XXXIII.) of the anterior pairs with three rather long papil- 

 lary and equal branchial lobes, the dorsal cirrus not reaching much 

 beyond their apices ; but the posterior feet much resemble those of 

 H. renalis. 



Although the size of an animal is not usually reckoned a good 

 specific character, yet we know that every species has in this respect 

 certain limits which it never either much exceeds or falls short of. 

 For this reason, it seems to me impossible to regard Heteronereis lon- 

 gissima as a variety of H. renalis, notwithstanding the similarity in the 

 structure and figure of the feet would induce that belief; and I have 

 been fain to resort to the distinctions afforded by the jaws and pro- 

 boscis for their separation. This is the only known species with a 



