Till: BRACEIOPODS. t 7 



ciliated Larva like that of the true worms, which after Bwim- 

 ming about finally becomes fixed by a .-talk to roi i . 



W'hili in their development the Brachiopods recall th> 

 larva' of the true worm.-, thej resemble the adull worms in 

 the general arrangemenl of the arms and viscera, though 

 the\ lack the highly developed nervous system of the Anne- 

 Lids, as well as a vascular system, while the body is not 

 jointed. <>n the other hand they are closely related to the 

 Polyzoa, and it Beems probable that the Brachiopods and 



Fio. tB.—IAnffula pyramidata with Its Band-tube; natural size. 



Polyzoa were derived from common low vermian ancesi 

 while the true Annelids probably sprang independently 

 from a higher ancestry. They are also a generalized typo, 

 having Borne molluscan features, such as a bivalved shell, 

 though having nothing homologous with the foot, the shell- 

 gland or odontophore of mollusks. 

 The class of Brachiopods is a very anci< ni one, nearly 



2000 species of fossil Brachiopods being known. One living 



species of Lingula (Fig. 62) differs bul slightly from the 

 most ancient fossil Bpecies. It lives buried in the sand, 

 where it forms a tube of Band around the -talk, just below 



low-water mark, extending from Chesapeake Bay to Florida. 



Lrn rati i.i 



A. Huneot'k. On the Organization of the Brachiopoda. Phil. 

 Trans. 1868 



B. 8. Morse, On the Systematic Position of the Brachiopoda. 

 Proc Boston Soc Nat. Hist., w . I 1 -;::. 



With the essays of Brooks, Lacaze-Duthiers, Kowalevsky, Dall, 

 etc. 



