INVERTEBRATES OF UNCERTAIN POSITION 



185 



Plnmatella and Pectinatella are fresh-water 

 Ectoprocta. The Entoprocta have the 

 anal opening within the lophophore, and 

 the space between the intestine and body- 

 wall is filled with mesoderm cells. Pedicel- 

 Una and Umatella belong to this group. 



8. Phoronidea 

 This group consists of a single genus, 

 Phoronis (Gr. Phoronis, name of a king, 

 Fig. 125), containing worm-like animals 

 which live in the sand, enclosed in mem- 

 branous tubes. Their systematic position 

 is still more or less uncertain, but their 

 structure indicates a probable relationship 

 to the Ectoprocta. 



9. Brachiopoda 



Fig. 125. — Phoronis 

 buskii (of the group 

 Phoronidea) removed 

 from its tube and seen 

 from behind. (From 

 Sedsrwick after I^[ In- 



The Brachiopoda (Gr. brachion, the t osh.) 

 arm; pons, a foot) are marine animals 

 living within a calcareous bivalve shell (Fig. 126). They are 

 usually attached to some object by a peduncle (Fig. 127, 10). 



wit 



Fig. 126. — Magellania ftavescens (of the group Brachiopoda). A, dorsal 

 aspect of shell. B, shell as seen from the left side. b, beak; d.v., dorsal valve; 

 /, foramen; v.v., ventral valve. (From Weysse, after Davidson.) 



