APPENDIX B 



641 



the latter. Mouth enclosed in a crown of tentacles, the lophophore, a characteristic 

 structure; intestine U-shaped, with anus near the mouth. Bryzoan colonies often 

 bear a superficial resemblance to hydroid colonies, and many secrete coral-like 

 skeletons. This group is sometimes combined with the following one to constitute 

 the phylum Molluscoidea. About 1,200 known species. 



BRACHIOPODA (brak' i op' o da). Lamp shells (Fig. 27.1). Body unseg- 

 mented and covered by a calcareous (limy) two-valved shell, which often has the 

 appearance of an ancient form of lamp. The shells cover the dorsal and ventral 



Fig. B.10. Rotifers and other minute organisms in a tiny portion of a pond. Above, center, 

 a trap bladder of the flowering plant Utricularia, ready for victims. Left, a spherical (radiat- 

 ing) colony of the rotifer Conochilus hippocrepis. Lower left, a large solitary rotifer, Dicrano- 

 phorus forcipatus. Diatoms and other algae are lodged on the Utricularia branches. (Cour- 

 tesy American Museum of Natural History.) 



surfaces instead of the lateral surfaces, as in the clams and mussels (phylum 

 Mollusca). The mouth is situated between two looped ciliated arms (lophophore), 

 which lie coiled within the shell; the ciliated food canal may end blindly or be 

 provided with an anus near the mouth; the body may be directly moored to the 

 substratum or be attached by a stalk (pedicel) from the posterior region. More 

 abundant in past geological periods than at present, thousands of fossil species 

 being known; 500 living species, all marine. 



Phylum VII. ECHINODERMATA (e kin' o der' ma ta; Greek, 

 echinos, "hedgehog/' referring to the spines, and derma, "skin"). 



Starfishes, brittle stars, sea urchins, sea cucumbers, sea lilies. Complex 

 Metazoa, typically with the following characters: 



