POLYCHAETE WORMS, PART 1 299 



First or buccal segment achaetous, distinct or more or less fused with 

 prostomium, without tentacular cirri or tentacular palps (as in 

 Spionidae), usually with a pair of nuchal organs or slits. Parapodia 

 biramous, essentially without setal lobes, without internal acicula, 

 \vith conical, cirriform or filiform postsetal notopodial lobes (some- 

 times referred to as dorsal cirri) and with or without postsetal neuro- 

 podial lobes (sometimes referred to as ventral cirri) on some anterior 

 segments. 



Setae all simple, smooth or faintly striated (not crenulate or ringed 

 as in Orbiniidae), of various Idnds: slender, capillary; limjjate, 

 capillary, faintly striated; crotchets or acicular setae on some posterior 

 segments; lyi-ate setae. Branchiae dorsal to notopodia, simple, 

 paired, straplike or wide foliaceous, cUiated, absent from few anterior 

 segments (3-6) and a long posterior region (4-60 pairs of branchiae). 

 Anal cirri 2-3. Anterior region of digestive tube evaginable as a 

 cylindrical or feebly lobed proboscis. Intestine contains numerous 

 greenish granules in intestinal epithelium. 



The paraonids live in mud or sand where they may be surrounded 

 by a thin tube of sand cemented by mucus but without any firmness. 

 They are evidently bottom-deposit feeders; sand grains may be found 

 in the gut. The anterior branchial part may be more or less straight, 

 the more posterior part may cmi up in a tight spiral or in a knot. 

 The anterior part typically is pale pink, the more posterior part taking 

 on a greenish tint. Some paraonids have pelagic larvae recalling 

 those of the spionids, minus the tentacular palps. The paraonids are 

 probably more widely distributed than their sparse records might 

 indicate, since they are in general very small, slender, threadlike, 

 dehcate, and easily overlooked. 



Key to the Genera of Paraonidae 



1. Without dorsal antenna (fig. 79a) Paraonis (p. 299) 



With dorsal median antenna (fig. 80,a,h) Aricidea (p. 303) 



Genus Paraonis Grube, 1873 



Levinsenin Mesnil, 1897; type (herein designated): Levinsenia fulgens (Levinsen, 

 1883). 



Type (monotypy) : Paraonis tenera Grube, 1873. 



Subgenus Paraonidcs Cerruti, 1909 



Type (monotypy) : Paraonis (Paraonides) neapolitana Cerruti, 

 1909. 



The species represented have the body slender, cyhndrical, slightly 

 flattened anteriorly. Prostomium conical, lacking a median antenna, 

 the anterior end terminating in a sensory tip (sometimes referred to 

 as a terminal tentacle or palpode) which may be invaginated, with a 



569-457—63 20 



