REPORT ON THE MONAXONIDA. 263 



We may briefly sum ujd our conclusions with regard to the geographical and 

 bathymetrical distribution as follows : — 



1. The Monaxonida as a group are cosmopolitan. 



2. They are most abundant in the Indo-Australian area. 



3. Individual species have not usually a very wide range, and rarely or never 



except in the case of generalised types, or where the conditions of life are very 

 similar, as in the case of Axinella lyrofunda. 



4. They are most abundant in shallow water and gradually decrease in numbers 



as we go downwards. The limit of depth, so far as we at present know, is 

 3000 fathoms. 



5. The shallow- water species are characteristically without any definite, sym- 



metrical external form ; but in the abyssal species a perfectly definite and 

 usually symmetrical external form is almost invariably present. 



