92 HELEN L. M. FIX ELL ON 



Spirorbis patagonicus (Caullery and Mesnil), 1897 (1, p. 205); Ehlers, 1901 



(5, p. 224). 

 Specific characteristics : 



1. Talon of operculum, a prolongation of the terminal shallow funnel. 



2. Collar-se-tJB small, with a fin-like expansion at the base of finely serrated 



blade (fig. 4, a). 



3. Numerous sickle-shaped setae to 3rd thoracic segment. 



4. Abdominal setae large, flattened, and trumpet-shaped. 



5. Large somewhat irregularly coiled tubes. 



Localities. Several specimens on the shell of Mytilus, from Station 478, Table Bay, 

 Cape Town Docks, May 1904. Other specimens, with Spirorbis falklandicus, on a 

 stone from the shore at Station 118, Port Stanley, Falkland Islands, January 1903. 



Most of the tubes are rather smaller than those described by CAULLERY and MESNIL. 

 They are generally loosely and irregularly coiled. All ages seem to be represented, and 

 both the young with three thoracic segments only and the adults agree with the 

 descriptions given by these authors. 



There are apparently ten branchiae, including the opercular pedicle, and about 

 twenty abdominal segments. The largest specimen obtained whole from its tube 

 measured 6 mm. 



Paradexiospira Caullery and Mesnil (l, p. 195), emend. Pixell (15, p. 793). 



Spirorbis falklandicus, n. sp. 



1. Last thoracic segment without dorsal setae. 



2. Collar-setae small, very finely serrated blades with large fin at base. 



3. Operculum very similar to that of S. vitreus. 



4. The 3rd thoracic fascicle contains bladed sickles (setae of Apomatus) (fig. 5, r). 

 Several specimens, with S. patagonicus, on a stone from the shore at Station 118, 



Port Stanley, Falkland Islands, January 1903. 



This is the first time that a species of the sub-genus Paradexiospira has been 

 recorded from the Southern Hemisphere. CAULLERY and MESNIL (l,p. 195) state that 

 the three species known to them, namely S. cancellation Fabr., S. vitreus Fabr., and 

 S. violciceuK Lev., inhabit Greenland and Iceland. S. vitreus has since been found in 

 the North Pacific (15, p. 793). 



The tubes of Sjiirorbix falklandieus generally have three longitudinal ridges, the 

 median one sometimes ending in a projection overhanging the mouth of the tube. The 

 terminal part may be more or less ascending, and is rather more than 1 mm. in dia- 

 meter. Only about one and a half turns of the spiral can be seen from the top, and the 

 tube measures 3 mm. across. 



Branchiae ten, the second on the right bearing the operculum, as usual. In young 

 specimens the operculum is almost flattened on the top, and has a massive, sometimes 



(ROY. soc. KDIN. TRANS., VOL. XLIX., 352.) 



