Plate XX. 



Page 

 Fig. i. Melonanchora elliptica Cart, a styli, one with rounded point, b tylota, x 200, c sphser- 

 ancora of long elliptical form, d the same of broad elliptical form, both with the ori- 

 ginal axis to the right, e young developmental form, f older developmental form, 

 g developmental form with nearly connected teeth, // developmental form with the 

 four arcs formed, but without the striated brims, the original axis to the right, i form 

 with beginning striated brims, k arc with nearly fullgrown striated brims, I transverse 

 section through fully developed arc, showing the median part and the side-brims, 

 x 700, in ancora of the large form, front view, a little oblique, and side view, n deve- 

 lopmental form, ancora of the small form, front view and side view, x 700 211 



— 2. Melonanchora emphysema O. Schmidt, a tylota, x 200, b sphaerancora, x 700, c ancora 

 of the large form, front view and side view, d ancora of the small form, side view, 



i o v 



x 700 216 



3. Forccpia groenlandica Frstdt. a acanthostylus, b tylotum, x 200, c chela arcuata, front 



view and side view, x 1000, d forceps, x 1000, e sigma, x 460 209 









