BY VERA lEWIN-SMITH. 233 



extended specimens. Almost boiling 70% alcohol gave much the best results. 

 70% alcohol had been used to fix and preserve lot A, and most of these specimens 

 were in very good condition, though the caudal extremity in a number of the 

 females was very contracted, and the cuticle showed some abnormal distension. 

 All the specimens of lot C were fixed in hot glycerine alcohol, but some of them 

 were subsequently transferred to 70% alcohol, and after dehydration and treat- 

 ment with cedar oil or clove oil made successful Canada balsam mounts. In these 

 cases the oil was added to the absolute alcohol in gradually increasing strengths, 

 from one third, one half, two thirds, to the pure oil after three days, and the 

 specimens remained quite clear when mounted, and showed details of internal 

 structure well. Cedar oil proved better than clove oil. Other mounts were made 

 in glycerine jelly, after clearing in glycerine by the gradual evaporation of the 

 glycerine alcohol. But with these stout-bodied worms the jelly mounts were not 

 clear enough for good microscopical examination, though papillae and other 

 cuticular structures showed up better than in any other medium. Glycerine also 

 proved a vei-y good medium in which to dissect the specimens. The most useful 

 reagent, however, both for rapid microscopical examination, and for clearing and 

 preserving specimens during dissection was alcoholic phenol, used in the propor- 

 tions of 80 parts phenol to 20 parts absolute! alcohol, though permanent mounts 

 could not be made from these preparations. 



Superfamily SPIBVROIDEA Railliet & Henry, 1915. 



Family ACUARIIDAE Seurat, 1913. 



Subfamily PHYSALOPTERINAE Seurat, 1913. 



Genus Phy salopteea Rudolphi, 1819. 



Species Physaloptera Antarctica Linstow, 1899, var. typica. 



Body robust, elongated, slenderly and evenly proportioned, of a uniform 

 diameter in the middle region, tapering at each extremity. Cuticle thick, un- 

 dulant, densely striate transversely, the striations very fine and inconspicuous; 

 cephalic collarette large. Post-cervical papillae thorn-shaped, situated on the 

 lateral lines in depressions in the cuticle, slightly behind the junction of muscular 

 and glandular oesophag-us (Text-fig. 23), at an average distance of .5 to .7 mm. 

 from the anterior extremity, according to the length of the worm. Excretory 

 pore on the ventral median line, .08 to .09 mm. behind the post-cervical papillae 

 (Text-fig. 1). Lateral lips slightly trilobed, the buccal pads, applied to them 

 externally, thick and hemispherical, bearing the paired lateral papillae (Text- 

 fig. 3). External labial tooth stout and conical, with a small, deeply-notched, 

 double-pointed tooth at its base internally. The small bicuspid tooth, situated 

 internally on the summit of eaeh lateral lobe of the lip, widely notched to the 

 base, the cusps short and broad (Text-fig. 4). The internal denticular border 

 made up of a group of three fairly large, sharply-pointed denticles on each side 

 of the base of the median tooth, and a line of five or six similar denticles down 

 each side, each group being continued by a few very minute and indistinct den- 

 ticles, not always visible, along a well-marked curved line forming the inner 

 edge of the lip. Buccal cavity short; oesophag-us in two parts, the anterior part 

 muscular, usually less than one-eighth of the total length, narrower than the 

 glandular oesophagus, which expands just behind the junction and has an almost 

 uniform diameter throughout. Glandular oesophagus conspicuous by its dark 

 colour, the transition into the lighter muscular oesophagus well marked (Text- 



