POLYCHiETA--BENHAM. 89 



Dimensions of tubes — S. mirahilis, Mcintosh, 1 ;"0-l fiO mm. by 4 mm. ; F>. spinifera, 

 Thiers, Gravier and myself, 150-240 mm. by 5 mm. 



Geographically and bathymetrically, the two " species " overlap. Both were 

 obtained from Kaiser Wilhelm TI Land ; and 8. spinifera extends up the west coast of 

 South America to Valparaiso (Mcintosh), while 8. mirahilis occurs up the east coast as 

 far North as Rio de la Plata (Mcintosh). 



The depth at which the two forms have been obtained varies from 110 fathoms 

 (" Aurora ") to :i534-7 fathonis (" Valdivia "). These have the " spinifera " form of 

 tube, while the 8. mirahilis form comes from 212 fathoms (Elilers) to 600 fathoms 

 (Mcintosh). 



It is then evident that Ehlers was fully justified in liLs expression of doubt as to 

 the distinctness of the two species, and it must of course retain the name bestowed upon 

 it by Mcintosh. 



Locality . — 



Commonwealth Bay — 



Station 2,318 fathoms (two). 



,, 8,120 fathoms (four, the one studied is a male). 

 ,, 12,110 fathoms (a female distended with eggs). 



Distribution. — Off Valparaiso, off Eio de la Plata (Mcintosh), south of Bouvet 

 Island, Kaiser Wilhelm II Land ( Ehlers) , Graham's Land ( Gravier). 



Genus le.bna Malmgren. 



Le.ena arenilega Elders. 



Ehlers (1913), p. 504, pi. XLIV, figs. 8-13. 



(Plate 9, figs. 95, 96.) 



Two specimens only were obtained during this expedition, which is in contrast 

 witli the abundance of the worm off Kaiser Wilhelm TI Land. 



The present specimens show some apparent differences in the structure of th 

 " head " from that described by Ehlers, but whether these are due to differences of 

 preservation, or of interpretation, or of state of development, or are specific, it is difficult 

 to decide when so few iiidividuals are available. But since the worms agree in all 

 essential features with his account I attribute them to his species, but add figures to 

 illustrate the apparent discrepancies. 



The tube is long and narrow, measuring 100 nim. in length by 3 mm. in width. 

 It is built up of a single layer of transparent, colom'less sand-grains with a slight admixture 

 of otlier material, such as sponge spicules : the outer surface is rough, and the grains 

 seem very loosely adherent. It is more or less undulating, as if it had been coiled amongst 

 other objects. 



