Pomona Colleije, Clarcmont, California I'' 



is found in the tentacles where there is a combination of sensory 

 cells at the base of the sense organ. 



The retrocerebral apparatus in Eosphora consists of two glands 

 lying back of the brain. They are covered with membrane and so 

 not in direct connection with the brain. One of these glands is the 

 pear-shaped retrocerebral sac which is clear with vacuoles. If 

 this is in any way a sense organ it is a question what its function 

 would be. 



In Eosphora there is a single eye on the surface of the brain 

 and two slightly pigmented knobs at the anterior margin of the 

 animal ; these have a direct connection with the brain and must be 

 sense organs, possibly something like eye spots. 



Gastrotricha. In 1864 Gosse described a knob on the oesoph- 

 agus as the brain in Chaetonotus. Ludwig in 1875 described the 

 nervous system on the side of the brain. Butschli, 1876, added 

 nothing of importance and Fernald, 1890, did not see the brain in 

 Chaetonotits. The clearest recognition of the nervous system was 

 by Zelinka in 1890. A large brain in the head region surrounds 

 the gullet above and on the sides and a pair of nerve trunks extend 

 down the body. Cephalic sense hairs are directly connected with 

 nerve cells of the brain. The hairs of the body may be for touch 

 or possibly smell or taste. Simple eyes have been described for a 

 number of species in the back part of the head, as small red spots, 

 but not all species possess them. 



KiNORHYNCHA. Claparede in 1863 describes a nervous sys- 

 tem in this group and others at an early time also figure or describe 

 something of the nervous system. Reinhard, 1887, believes that in 

 most cases the nervous system was not seen by the earlier investi- 

 gators. He describes and figures a ganglion on the oesophagus but 

 gives no details. Zelinka, 1894, describes a circum-oral ring and a 

 long ventral nerve strand. Schepotieff, 1907, describes a brain 

 above the oesophagus with two connectives and a ventral strand. 

 The nervous system is somewhat like that of Gastrotrichia with a 

 large upper brain of a large mass of three general parts all fused. 

 The ventral strand runs the length of the body but is not differen- 

 tiated into ganglia but has cells along its course. Eye spots have 

 been described in some species, the number being from 2-8. 



BIBLIOGRAPHY 

 Butschli, 0. 



1S7(). Untersuchungen uber freilebende hematoden und die Gattung 

 Chaetonotus. Zeit. f. wiss. Zoll. Bd. 26. pp. 363-413 Taf. 23-26. 



Claparede, E. 



1863. Beobachtungen ubei- Anatomie und Entwickelungsgeschichte wir- 

 belloser Thiere. An. der Kuste Normende pp. 90-92, Taf. 16, figs. 

 7-16. 



