536 



Forty- fifth Report on the State Museum. 



One pair extends to the caudal lobe and becomes the ventral 

 a — c 



Fig. 202.— Embryonic stages of Olottidia Audebarti. A, Dorsal view of the youngest embryo 

 observed; B, Dorsal view of a somewhat older embryo; C, Ventral view of an individual 

 goon after becoming sedentary; a, hinge-teeth of brachial valve; b, hinge-teeth of pedicle- 

 valve; c, semicircular plate of brachial' valve; d, median tentacle: /, parietal bands; g, body 

 cavity; h, liver; k, hepat.c chamber of stomach; i, iatestinal chamber of stomach; m, intestine; 

 n, anus; o, mouth; p, muscles; g. lophophore; r, posterior unpaired muscle; s, pedicle; 

 v, pallial sinus; w, its opening into the body ca ity; nu, edge of larval shell. (Brooks.) 



pedicle-muscles. The fourth pair extends 

 from the dorsal to the ventral wall of the 

 body, just behind the digestive cavity; 

 this becomes the diductor muscles. There 

 is a fifth pair of dorsal pedicle-muscles in 

 Liothyeina. 



Following this condition the four bundles 

 of setae are lost, the eye spots disappear, 

 the digestive tube and stomach become well 

 defined, the cilia of the brachia or lopho- 

 phore appear, and the valves of the shell, 

 which before had been simple plates upon 

 the surface of the mantle lobes, come 

 into contact about their lateral and 

 anterior margins. The animal lias now 

 taken on the appearance oi a brachiopod 

 and is a phylembryo. Later growth to 

 the adult condition consists in the per- 

 fecting of the details now outlined in the 



Fig. 203 — Diagrammatic 

 longitudinal section of 

 young of (iiciiKiid />. 

 pedicle valve; />, brachial 

 valve; a. umbonal muscle; 

 c, stomacl ; </, mouth; < , 

 lophophore; /, ganglion; 

 f/, horder of mantle.— 

 (Brooks.) 



"to 



embryo. 



88 



