Explanation of the Plate I. 



Aulacoctena acuminata Mrtsn. 

 Figs. 1 — 4 photographs by Docent R. H. Stamm; figs. 5 — 12 drawn by the author. 



Fig. 1. Large specimen, seen from the sagittal side. l -5 /i • 

 . 2. The same specimen, seen from the tentacular side. A thin glass tube has been laid into the lateral furrow, in order to make it 

 more distinctly seen in the photograph. The glass tube is seen in the upper half. The oral slit is a little widened. ,,5 /i ■ 



3. Small specimen, seen from the sagittal side. 1-5 /i • 



4. Fragment of a large specimen upper part, opened so as to show the folds of the pharynx; the lateral processes from the tentacular 

 bases are seen, also the apical invagination, in the slightly widened bottom of which lies the apical organ. Along the sides are 

 seen the proliferations from the subtransversal meridional vessels along the wall of the lateral furrow. |i5 /i . 



5. The same fragment as fig. 4, somewhat more dissected. The upper part of the pharynx is filled out by the large sagittal folds; 

 below these some proliferations from the pharyngeal vessels are seen in the pharyngeal wall. Between the openings of the subsagittal 

 adradial vessels (o. adr. v.) is seen the oesophagus with the thickened inner lips. ap. apical organ; inf. infundibulum ; inv. apical 

 invagination; 1. pr. lateral process from the tentacle basis; ph. v. pharyngeal vessel; pr. proliferations from the subtransversal meridional 

 vessels; s. w. side wall of the body: t. b. tentacle basis; t. sh. tentacle sheath. 3 /i . 



6. Lower end of the pharynx, ph. v. pharyngeal vessel, pr. proliferations from the subtransversal vessels ; s. t. v. subtransverse 

 meridional vessel; s. w. side wall of the body; t. sh. tentacular sheath. 3 /i ■ 



7. Tentacular basis, seen from the outside, adr. v. adradial vessel; 1. pr. lateral process from the tentacle basis; o. tr. v. opening of 

 the transverse vessel; ph. v. pharyngeal vessel; pr. ar. proliferation from the adradial vessel; t. sh. tentacular sheath. '%• 



„ 8. Proliferations from subtransverse meridional vessel, along the wall of the lateral furrow. 3 A . 



9. Terminal knob of the tentacle. I7 A ■ 

 . 10—11: Colloblasts. 73 %. 

 , 12. Muscle fibre with protoplasmic swellings. 73 % . 



