178 ODONTOSYLLIS FULGURANS. 



Eusyllis Blomstrandi from the close connection of the forms. As development proceeds, 

 the tentacle and additional pair of eyes posteriorly, the appearance of the adult pharynx 

 behind the larval and the gradual recrudescence of the latter and the completion of the 

 former, the growth of the proventriculus behind and in rear of it, the lateral cseca and 

 the intestine with its anus, the growth of the palpi subsequent to the tentacles, as lateral 

 buds, 1 the fusion of the base as they increase in size and pass to the front with their rich 

 coating of cilia and palpocils, and the completion of the alimentary canal, are all figured 

 and described by the author. There is much in common with the growth of Autolytus, 

 but the cephalic band of cilia does not appear till there are seven or eight bristled seg- 

 ments, at which time the dorsal ciliated bands also occur posteriorly. 



The author points out that he thus differs from Viguier, who described the develop- 

 ment of the proboscis as from behind forward, and who considered the larval pharynx as 

 the proventriculus. 



Genus LIL — Odontosyllis, Claparede, 1863. 



Palpi short or moderately elongated, more or less separate, or fused at the base. 

 Tentacles (three) and dorsal cirri filamentous, short. They become longer in the mature 

 (sexual) state. Nuchal organ has a central pit (Malaquin), and an occipital gibbosity occurs. 

 Tentacular cirri two pairs. Ventral cirrus present. Proboscis with a series of pointed 

 cuticular horny papillae, the points curved backward. 2 Ventricle (stomach) short and 

 devoid of T-shaped caaca. Bristles with terminal piece simple or bifid (Claparede 3 ). 



1. Odontosyllis fulgurans, And. and JEW., 1833. Plate XLIX, fig. 5; Plate LIX, figs. 

 15 and 15 a and b — head and tail ; Plate LXX, fig. 11— foot ; Plate LXXIX, fig. 4— 

 bristle. 



Specific Characters. — Head rounded, a Y-shaped groove dividing it into three regions. 

 Eyes four, large, the anterior with lenses, occasionally nearly forming a square. Palpi 

 moderately elongated. Median tentacle, which arises in front of the eyes, longer than the 

 two lateral. Body fully an inch in length with 60 to 100 segments, slightly tapered 

 anteriorly and more distinctly so posteriorly. A prominent papilla in the mid-dorsal line 

 occurs behind the head, giving gibbosity to the region. Tail with two median cirri and a 

 slight median process between them. Of an orange hue, or pale yellow in front and reddish 

 over the intestinal region behind. Whitish grains on the dorsum. Proboscis short, 

 with seven denticulations. Proventriculus long (extending to the sixteenth segment). 

 Foot distinctly bifid at the tip. Dorsal cirrus of moderate length, unjointed. The 

 dorsal edge of the setigerous lobe passes with a slight curvature to the spine, a deep 

 groove splitting the foot beneath. The dilated distal region of the shafts of the larger 



1 Malaquin compares these with the condition in Nerilla, Schmidt, op. cit., p. 412. 



3 Ehlers observes that the opening of the oesophagus has two transverse thickenings like teeth. 



3 Claparede mentions a bifid bristle (like that of Syllis gracilis) in a large specimen from St. Vaast. 



