Pomona College. Claremniit. California 81 



border of the superior adductor muscles. A large ventral commi.si- 

 sure unites the ganglia under the oesophagus. Each ganglion fur- 

 nishes the following nerves: (1) to the adductor inferior muscle, 

 a nerve with a little branch to the internal oblique muscle, (2) a 

 nerve to the dorsal part of the mantle. (3) a nerve to the ventral 

 part of the mantle, (4) a nerve to the arm, (5) branches which join 

 with the ventral oesophageal commissure, (6) several nerves form- 

 ing the dorsal nerve commissures. The dorsal commissure has 

 nerves going to the cirri. 



All nerves are under the skin. Cirri are probably organs of 

 touch. 



Heath, 1889, has found sensitive striae formed by high epith- 

 elial cells connected with the ganglion cells. These areas are along 

 the middle line on the ventral side. 



In spite of fragmentary and conflicting evidence the following 

 seems clear as the nervous system of brachiopods : 



A nerve ring surrounds the oesophagus; this is enlarged on 

 the dorsal side in a small inconspicuous ganglion near the base of 

 the lip. A larger suboesophageal ganglion is the thickening on 

 ventral side. The ventral ganglion and perhaps the dorsal retain 

 their primitive connections with the surface layer of the skin. Both 

 ganglia give off a nerve each side to the arms and along the base 

 of the tentacles and lips. The ventral ganglion also gives off nerves 

 which supply the dorsal and ventral folds of the mantle and the 

 muscles. In some cases the dorsal ganglion seems to be repi'e- 

 sented by a dorsal band only. 



Sense organs are doubtful: the margins of mantle and cirri 

 may have a tactile function and the epithelium on the surface of 

 the ganglia have been suggested as olfactory areas. 



BIBLIOGRAPHY 

 Bemmelen, J. G. Van 



1883. Untersuchungen ueber den Anatomischen unci histologishen Bau 

 der Braehiopoda Testicardinia. Jen. Zeit. f. Nat. Bd. 10, pp. 88- 

 161, pi. 5-6. 

 Beyer, H. G. 



1866. A Study of the Structure of Lingula (Glottidia) pyraniidata 

 Stein. J.'H. Univ. Stud. vol. 3, pp. 227-265, pi. 14-17. 



Blockmann, F. 



1892. Ueber die Anatomie und die verwandtschaftlichen Beziehung der 

 Brachiopoden. Arch. d. Fren. d. Nar. in Meek. Rest. pp. 37-50. 



1893. Anatomische Untersuchung ueber Brachiopoden. I Crania 

 anomala. Bib. Zool. 40, pp. 66, 7 pi. 



Gratiolet, P. 



1857. Etudes Anatomique sur la Terebratule .Australe. Jour, de Con- 

 cologie. vol. 6, 2 e ser. 2, pp. 209-258. 1 pi. 



