20 AUGUSTA ÄRNBÄCK-CHRISTIE-LINDE, NORTHERN AND ARCTIC INVERTEBRATES. 



ovary and ends close to the orifice of the oviduct. Both the oviduct and the vas 

 deferens open at the end of the gonad near each other. 



On the inner side of the mantle a large number of endocarps are visible. 



Remarks. 



In comparing Slyela theeli with other Styelids, it appears that, while it agrees 

 in some external and internal features with the members of the group Goniocarpa, 

 it is distinctly marked off from other species. No known Styela has gonad s which 

 agree with those of S. iheeli, nor a dorsal tubercle which resembles that of the latter; 

 even the alimentary canal shows different characters. In some respects S. theeli 

 resembles in appearence S. loveni: the leathery test, the expanded base and the 

 depressed form are features which remind one of 8. loveni. And as to the in- 

 terna! anatomy, it should be observed that the structure of the gonads offers several 

 points of agreement with the last-mentioned species. In both, the ovary is a sinu- 

 ously curved tube of considerable length and with the same characteristic bend, the 

 testis and the vas deferens show the same general plan of arrangement and structure. 

 The orifices of the gonads are in both species directed towards the atrial aperture. 



There exist, however, more essential differences. With regard to the external 

 aspect I would point out that S. theeli is of greater size, that it is attached by the left 

 side. It also differs in the condition of the test: the wrinkles and the arrangement 

 of the folds around the apertures are dissimilar. In the internal structure we find 

 important differences. If we compare the gonads of the two species, it will be evident 

 that, while agreeing in some general features, they differ in form and size, in the 

 inflated oviducts and above all in the number, a character which is considered to 

 be of great value in distinguishing the different groups of the family Styelidae from 

 each other. In no other known Styela there are, normally, two gonads on the one 

 side and only one on the other. In Styela loveni the presence of one gonad on each 

 side is considered to be constant. 



As far as concerns the number of the gonads, S. theeli might be regarded as 

 an intermediate form between the Goniocarpa group which has one gonad on each 

 side and the canopus group which has two gonads on each side. So far as one can 

 judge from this single specimen of S. theeli, there does not seem to exist any greater 

 resemblance between it and the latter group in any other respect. 



In regard to the systematical position of S. theeli it should be observed that, 

 though the species is no doubt nearly allied to the group Goniocarpa, it can not be 

 referred to this group without further evidence. If forms like S. theeli are to be 

 included, the definition of the group should be altered. Or a new genus must be 

 established. Provisionally, however, it may conveniently be referred under the genus 

 of Styela to the Goniocarpa group, until further specimens will ha ve been found, the 

 investigation of which will serve to complete the description of the species. 



So far as I am aware, no further specimen of S. theeli has vet been found in 

 the Norwegian fjords nor off the coast, and according to the literature on the subject, 



