20 THÉEL, PRIAPULIDS AND SIPUNCULIDS OF THE SWEDISH ANTARCTIC EXPEDITION 1901 — 1903. 



mittelbar iiber dem Schwanzanhang, einen Giirtel dicht neben einander stehender 

 Warzen hat, die, hell gefärbt, bei grösseren Exemplaren mit unbewaffnetem Auge gut 

 zu sehen sind. Dieser Giirtel wird auf eine grössere öder kleinere Strecke nur da 

 unterbrochen, wo längs der Bauchseite ein hervorstehender Wulst, nämlich die Bauch- 

 naclit durchzieht. In allem Ubrigen imterscheidet sich die antar ktische Varietät von 

 P. caudatus nicht mehr, als die einzelnen Exemplare des letzteren sich unter einander 

 unterscheiden ;....» 



Bnt now it is a fact, that all the specimens from Greenland, Spitzbergen, the 

 west coast of Sweden, the Baltic etc., which have been examined by myself, are 

 provided with such a girdle of warts round the extremity of the body in front of 

 the caudal appendage. And this girdle, too, is always broken on the ventral surface, 

 just as is seen on pl. I. figs. 9—11 and in the figures 4—6 in the text, giving rise 

 to a wider or narrower space in the median line, where the annulation of the body- 

 wall itself is more or less conspicuous. The figures referred to show that there is a 

 great variation with regard to the size and extent of the warts and to the wideness 

 of the ventral median space devoid of them. This variation is independent of the 

 different localities where the worms have been caught, as it is quite as apparent in 

 animals living in one and the same place. 



Figure 5 on pl. I represents a ventral view of the posterior portion of a small 

 specimen from the Falkland Islands showing the »ventral empty space» with distinct 

 traces of an annulation. It should be borne in mind that this annulation is very variable 

 even in northern forms of Priapulus, and that it in some cases is almost inconspicuous. 



In view of the above-mentioned facts, it lies very near to draw the conclusion 

 that the arctic and antarctic forms of Priapulus resemble each other in all respects 

 This, however, is by no means the case. For a closer investigation reveals that there 

 really exists a constant distinction between them, which has escaped the attention 

 of previous authors. Though this distinction seems to be constant and invariable 

 and consequently not unimportant, I am nevertheless in doubt whether it is of such 

 nature as to be of specific value. The dissimilarity is to be found in the structure 

 of the teeth. 



Seeing that no true distinctions have been indicated by previous authors, I 

 decided to undertake a detailed investigation of their teeth, and at my request the 

 skilful artist Mr Georg Liljevall began the arduous task of drawing them on an 

 enlarged scale. The results are shown on plate I, where the three great figures 

 represent views of the dentary apparatus of an arctic and antarctic Priapulus caudatus 

 Lam. and, besides, of an arctic Priapulus bicaudatus Dan. 



An inspection of the figures in question proves that the teeth of the three 

 specimens differ in some, more or less obvious, manner, though they are, of course, 

 constructed after the same plan. In order to illustratc their arrangement more plainly, 

 I have annexed to the text three diagrams. From these as well as from the plate I, it 

 becomes evident that the anterior sets of teeth are disposed in alternating regular pent- 

 agons, situated the one inside the other, and that they are provided with one large 

 central spine bearing one, two or several smaller secondary ones on each side. The order 



