HESIONIDJE. 115 



The few forms of the Hesionidee known were grouped by 0. Fabricius, Linnseus, and 

 others, amongst the Nereids. They formed the ninth genus of Savigny's Nereids. 

 Subsequent authors generally placed them near the Phyllodocidse and Syllidae, though 

 Benham separated them from the former by the Aphroditidse, with which they have little 

 in common. 



Grube first linked the HesionidaB to the Phyllodocidas — under the title Phyllo- 

 docea Hesionea. 1 In his last publication 3 on the Hesionea he defines the segments as 

 often 22, though they may reach 81. The head is rounded, rhomboidal, narrowed in 

 front, heart-shaped, with two or three simple, short, two- or three- jointed tentacles ; two 

 or three segmented sub-tentacles (CErsted's palpi). Two pairs of eyes. On each side 

 three or four (rarely one or two) tentacular cirri, slightly tapered, and sometimes with 

 short segments. Dorsal cirri thread-like, on a ceratophore ; ventral and anal cirri 

 shorter and devoid of a ceratophore. Foot simple or bifid; ventral bristles compound. 

 Proboscis long and cylindrical, or shorter and almost ovoid, smooth or sometimes with 

 a crown of papillae around the opening. In some, a tooth, as in the Syllidse, or a pair 

 of jaws, or papillae ; occasionally tooth and jaws combined. 



His main sub-divisions are : (1) Head with two very short tentacles, without sub- 

 tentacles (or with two). Fallacia, Hesione. (2) Head with two simple tentacles, and 

 two or three jointed sub-tentacles (palpi). Magalia, Kefersteinia, Gastalia, Periboea, 

 Syllidia, Psamathe fusca, Johnst. (3) Head with three simple tentacles and two sub- 

 tentacles. The ventral bristles with three teeth. Irma, Orseis, Oxydromus, Podarhe, 

 Gyptis, Ophiodromus, Tyrrhena, Leocrates, etc. In the foregoing synopsis he makes a 

 special genus (Kefersteinia) for Psamathe, Johnston, yet likewise includes under a separate 

 sub-section Psamathe fusca, Johnston, apparently having overlooked their identity. He 

 noted that in Stephania flexuosa, Claparede, the sexes were distinguished by their 

 colouration ; and that in the family generally the spines were black. In the Philippine 

 annelids he paid special attention to the armature of the proboscis as an aid in classifica- 

 tion. None of the British forms, however, show this condition. 



Ehlers (1864), who gives similar characters to Grube, characterizes the Hesionea as 

 having short flattened bodies with comparatively few segments, often brightly coloured 

 and transversely striped. The head is distinct — with tentacles only, or with tentacles, 

 palpi, and four eyes. The following segment has large tentacular cirri. Foot large, 

 single, or with a minute dorsal division ; jointed or simple capillary bristles ; long dorsal 

 and ventral cirri. Anal segment with lateral processes and anal cirri or papillae. The 

 extruded proboscis is short and smooth, and is followed by the stomach, the aperture to 

 which has or has not papillae. He grouped the genera as follows : (a) Head only with 

 tentacles. (1) Four tentacles. Hesione, Savigny. (2) Head with five tentacles. Podarhe, 

 Ehlers. (b) Head with both tentacles and palpi; palpi two-jointed, (a) Foot with 

 two well-marked divisions ; three tentacles. Ophiodromus, Sars. (b) Foot with a single 

 division, or with two, the upper tubercular; two tentacles. Gastalia (Sav.), Sars. 

 Ehlers (3) Palpi three-jointed, longer than the two tentacles. Periboea, Ehlers. 



i < Fam. Annel./ p. 58 (1851). 



2 Seniles, ' G-esellsch./ 1879. See also his work on the ' Philippine Annelids/ 1878. 



