SECT. IX EXCRETORY AND OTHER CxLANDS 139 



§ vii., where we stated that from their position 

 they were almost certainly excretory. 



The glands at the tips of the diverticula of the mid- 

 gut were also mentioned in the same section, and 

 were interesting as forming with the diverticula a 

 striking transition between the digesting diverticula 

 of the Annelids and the hepato-pancreas of the higher 

 Crustacea. 



The white oval spot, or dorsal organ, behind 

 the eyes in Apus we at first thought to be the 

 remains of an Annelidan frontal cirrus such as that 

 shown in Fig. i. It appears to be an island of dermal 

 glandular cells, the last remains of the Annelidan 

 dermal glands, which the thickening exoskeleton 

 probably rendered impracticable. This organ will 

 be described in detail in Appendix IV. It offers 

 indirect support to our theory of the Annelidan origin 

 of Apus. 



