KONGL. SV. VKT. AKADEMIENS HANDLINGAR. BAND. 15. N:o 7. 19 



The perigastric cells are round and oval with a plairi round nucleus whcn fully 

 developed. The cells are of many different sizes (tig. 7. h). 



The cephalic lobe is very large and rounded, and, taken together with the follow- 

 ing segment or segmentuin buccalc, larger tlian the two tirst spine-earrying segments of 

 the body. The front part of the worm is dark yellow, the 1 ii ti cl part being of a more 

 milky colour (tig. 7. b). 



The length of the body about 15 m. un. 



The width of the same about 1 m. m. 



The number of segments about 52 well separated, hut witli a very slight fene- 

 stration. 



The spines are curvate of nearly equal length in each fasciele 5. 6. 6. 5. (tig. 7. c). 



Habitat. Novaja Semlia at Karmakul and Gusinnoj Cap, about 72° 30' lat. 



A. Dicksonii can easily be recognized even without dissection by its large head 

 lobes, its deep yellow colour in front and its milky coloured tail, all giving the worm a 

 characteristic appearance. The principal anatomical characteristics are derived from the 

 form of the receptacle, the form of the cephalic ganglion, the peculiärly wound tube 

 of the efferent duct and finally from the perigastric bodies, which are of many dif- 

 erent sizes, the largest ones being the most highly developed. 



5. Archieuchytr«us gcmmatus n. sp. 



Pl. V. Fig. 8. 



The supra-cesophagial ganglion is very broad and square, the length however be- 

 ing greater than the width, and in that respect similar to same organ in the following 

 species (hg. 8. d). 



The enlargement of the receptacle begins in the middle, where it is narrowest, 

 from there' increasing in size towards the top (Hg. 8. e). 



The vesicle of the efferent duct is twisted and screwlike, and the penis is ver} 

 large or about 1 / 2 the size of the vesicle (hg. 8. f). 



The inner tube of the segmental organs is lobelike and very wide or of about 

 half the width of the middle lobe, hut not so long. The outer tube is longer than 

 the middle lobe but very narrow (fig. 31). 



The ovaries are in the ll th and 12 th segments. 



The testes are in the 8 th , 9 th and 10 th segments. 



The perigastric cells are large and round, seen from the side oval (fig. 8. h). 



The number of segments about 52 very well defined. 



The spines in each fasciele about 5. 6. 6. 5., the inner ones a little shorter than 

 the outer ones. 



Habitat. A few specimens were collected on Novaja Semlia, at Jugor Scharr 

 (69° 40'). 



The most distinct character of this species is the width of the inner tube of the 

 segmental organs. The shape of the receptacle is also of great value as a character, 



