86 AUSTRALASIAN ANTARCTIC EXPEDITION. 



The anatomy agrees with the account of S. spinifera given by Ehlers ; but as his 

 drawings of the animal are not very clear in certain points, I add a couple of somewhat 

 diagrammatically constructed figures in order to show the morphological relations of the 

 " lateral flaps," &c. (figs. 97, 98). 



In 1913 Ehlers hesitatingly suggested that possibly the two species, S. spinifera 

 Ehlers and Scione (Pista) mirabilis Mclntosh, are identical, for in writing of the specimen 

 of S. mirabilis from Kaiser Wilhelm II Land, he remarks (p. 562) : 



" Nicht vollig gehobene Zweifel bestehen dariiber, ob die Wiirmer nicht 

 identisch mit der von mir im vorstehenden erwahnten S. spinifera Ehl. sind." 



He then goes on to discuss the few differences which are, as he terms them, 

 " insignificant," and I may add comments on the four points to which he pays 

 attention. 



(1) " The differences in the structure of the tube may be due to differences 

 in the nature of the sea-bottom, and other conditions of the habitat." 



The characteristic feature of the tube both of S. spinifera and S. mirabilis is the 

 presence of long, slender, flexible processes or " spines " which project from its surface 

 and may be longer than the diameter of the tube. 



In Mclntosh's species the tube is cylindrical and the spines appear to be scattered 

 all over the surface without any regular arrangement, but in the original account of 

 S. spinifera Ehlers states that they are arranged in longitudinal rows. The tube figured 

 by Gravier (pi. XII, fig. 156) as S, spinifera is likewise cylindrical with processes 

 irregularly disposed. But more usually in those worms attributed to Ehlers's species 

 they arise from definite ridges which extend almost throughout the length of the tube' 

 and these ridges give it a very characteristic appearance, which was first figured by 

 Mclntosh (though without a name) and later by Ehlers under the title S. spinifera. He 

 and Mclntosh found three such ridges, but in the present collection each of the two 

 tubes which I received has four ridges. I find that at about the region at which the tube 

 curves over at its upper end these ridges die out and the spines lose their linear arrange- 

 ment and extend irregularly over the surface. Ehlers (1913) notes, too, that the ridgei 

 die out at the lower end in his species, though this is not the case with those before me. 



The material of which the tube is composed is a thin leathery membrane with 

 fine particles of mud worked up with the secretion. These mud grains are arranged in a 

 very regular fashion, as described and figured by Mclntosh for his unnamed tube ; they 

 are disposed in narrow circles round the circumference, each circle overlapping the next 

 b elow. In S: mirabilis Mclntosh observed sponge spicules embedded in the mud, 

 closely arranged parallel to one another, around the tube ; and similar spicules contribute 

 to the support of the processes or spines where they are arranged lengthwise. These 

 spicules were also found by Ehlers in his specimen of S. mirabilis (1913), but he did not 

 find them in the tube of S. spinifera, 



