KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 63. NIO 2. 17 



are a great many intermediate forms. Both types are represented in the col- 

 lections examined, those belonging to the flattened one seem to be more numerous. 

 After comparison betvveen specimens dredged in the fjords of the Arctic Norway 

 Bjerkan (1905) has expressed the view that the variation of the form of the body 

 might depend on the locality, the tall form having been found in comparatively 

 still water, the low one in strongly streaming water. From the material here exa- 

 mined nothing can be stated for oertain as to that view. From the Kola Peninsula, 

 for instance, there are small individuals of the flattened type and larger ones of the 

 tall type (PJ. 1, fig. 3). Among the specimens collected off the Swedish coast both 

 forms are represented. However, the observation has been made that specimens attached 

 to the test of other individuals, e. g. Polycarpa pomaria, usually belong to the tall 

 type, those attached to shell fragments or stones mostly belong to the low type. 



In the collections from Spitzbergen there are specimens characterized in a 

 special way. As appears from Pl. 1, fig. 4 representing a large individual in natural 

 size from Danes Gat, the basal part of the test is inflated and the surface is covered 

 with short, filiform processes incrusted with sand. The upper part is wrinkled and 

 formed like a cap. According to Hartmeyer (1903, p. 211) this form is characte- 

 ristic of the individuals from Spitzbergen and distinguishes them from Subarctic ones. 

 The material here examined does not verify that statement. In animals from the 

 Swedish coast the test shows the same differentiation though less developed. Bjerkan 

 has observed it in specimens dredged in the North Sea. From Actinia Bay there 

 are specimens which show the same external character. To that may be added that 

 even specimens from Spitzbergen vary; in the collection examined there are indi- 

 viduals which have a high cylindrical form, without the above-mentioned differen- 

 tiation of the test. In some specimens from Greenland the lower part of the test 

 is inflated and wide, but the surface is smooth, without filiform processes. 



The surface of the test is usually covered with small tubercles, it is wrinkled, 

 incrusted with sand, or smooth. In living specimens from Gullmarn the test is of a 

 brown reddish colour. 



As to the internal structure the examined individuals generally agree but for 

 the internal longitudinal vessels which show a highly varying number both on the 

 folds and on the interspaces between the folds. In large specimens they are often 

 more numerous than in smaller ones. The intermediate vessels are typically three 

 in number (ef. Hartmeyer 1. c. p. 210). In an individual from Kola, height about 

 17 mm., I have found 7 — 8 intermediate vessels between the folds and 10 along every 

 side of the endostyle. The usual form of the opening of the dorsal tuberele is ring- 

 shaped, in the specimen from Kola it has the form of the inverted letter S. In the 

 same animal the margin of anus shows only 5—6 lobes. The usual number is 12—14. 

 Whether those differences fall within the range of individual variation or not can 

 be decided only after the study of a more ample material. 



Styela loveni occurs, like S. rustica, in both the Arctic and the Boreal regions. 

 However, it seems to have its centre of distribution in the latter, being found there 

 more abundantly than in the Arctic, where it is sparingly met with. Is is abundant 



K. Sv. Vet. Akiid. Handl. Band 63. N:o 2. 3 



