Introduction to A n imal Morphology. 253 



pharyngeal ganglion, sending two lateral, visceral 

 branches, which form two small, lateral oesophageal 

 ganglia, and end in two labial ganglia. From the 

 large ganglia come off laterally nerves to the upper 

 mantle lobe and to the arms. Two cords pass beside 

 the oesophagus, forming a pillar-like pair ofgangli- 

 form swellings, sending branches to the ventral mantle 

 lobes. There is no oesophageal ganglion in Lingula, 

 but two lateral ganglia, sending many radial nerves 

 in the mantle. Two similar ganglia exist in Discina. 

 Most Brachiopods are hermaphrodite ; a few (The- 

 cidium, &c.) are dioecious. The sexual gland is afour- 

 (rarely two-) lobed yellow mass, either in the body 

 cavity, and partly round the intestine and muscles 

 (Ecardines', or in the space between the mantle lobes. 

 (Testicardines). How impregnation occurs is un- 

 known ; but as they are always in clusters, there 

 would not be much difficulty. The sexes in Thecidium 

 differ in the shape of their shell, and this genus has 

 also a brood-pouch wherein the eggs are retained by 

 fine filaments. The embryology of Brachiopods con- 

 firms strongly their relationship to Vermes. The ova 

 udate ciliated bodies, early develop- 

 ing a bilobed mantle, and a velum or ciliated 1 

 lobe, on each side of which are four, hollow, ciliated 

 process -s. The free larva has two ear-vesicles on the 

 , disappearing in the adult. I 

 :ient spots, which als<, The 



, and tl dilied 



into the arm 



found attached to th< d the 



'i found with many 

 embryo shells within it. Some L 



