94 



ACTINIARIA 



mesenteries of the ventrolateral pairs are the younger, the dorsal mesenteries of the same pairs the older. 

 The muscle-pennons are provided with high, mainly in the outer parts ramificated folds. In the upper part 

 of the reproductive region, at some distance from the actinopharynx, there are, in transverse-section, about 

 20 folds (textfig. 119); in the lower part of the reproductive region they are less numerous (textfig. 120). 

 The outer lamellar part of the mesogloea of the mesenteries issues from the exterior border of the pennon. 

 The parietal muscles are but slightly developed. On the pennon-side the short and sparse folds of the parie- 

 tal muscles merge into the longitudinal muscles of the pennon, now there are some rather close folds not far 



Fig. 119 



Fitr. 120 



Fit;. 121 



Textfigs. 119 — 121. Acthelmis intcstinalis. Fig. iig: Transverse section through a perfect niesenter)- in the uppermost part of 

 the reproductive tract. Fig. 120: A similar section farther clown through mesenteries of the first and second order. Fig. 121: 



A similar section of a mesentery of the second order. 



from the pennons, now some higher folds are developed in the middle part of the lamellar region of the me- 

 senteries between the column and the pennon (fig. 119). On the side of the mesenteries opposite to the pen- 

 non the parietal muscles form some sparse folds (textfig. 120), further upwards the folds are stUl sparser, 

 until at last they disappear, and a straight muscle-lamella remains. In the region of the ciliated streaks the 

 parietal muscles are of the same appearance (textfig. 119). The mesenteries of the second cycle are weak, 

 and their muscles with the sparse folds recall on transverse-sections the parietal muscles of the mesenteries 

 of the first cycle in the lower part of the reproductive region (textfig. 121). The mesenteries of the third cycle 

 are still more weakly developed. On transverse-sections I have observ^ed one stoma in the vicinity of the 

 actinopharj-nx. The mesenterial filaments are provided with well de-\'eloped ciliated and intermediate streaks. 

 Only the first 6 perfect mesenteries have reproductive organs. 



Remarks: The Greenlanders call this species "Kettuperangsak" (Fabricius). 



