74 MANUAL OF ZOOLOGY. 



SUB-ORDER II. PERFORATA. Test perforated by pseudopodial fora- 

 mina, generally calcareous. 



Family I. Lagenida. 

 n 2. Globigerinida. 

 ii 3. Mimmulinida. 



CLASSIFICATION OF THE FORAMINIFERA ACCORDING TO REUSS. 



L FORAMINIFERA WITH A NON-PERFORATE TEST. 



A. With arenaceous tests. 



1. Lituolidea. 



2. Uvellidea. 



B. With compact, porcellanous, calcareous tests. 



1. Squamulinidea. 



2. Miliolidea. 



3. Peneroplidea. 



4. Orbitulitidea. 



II. FORAMINIFERA WITH A PERFORATE TEST. 



A. With glassy, finely porous, calcareous tests. 



1. Spirillinidea. 



2. Ovulitidea. 



3. Rhabdoidea. 



4. Cristellaridea. 



5. Polymorphinidea. 



6. Cryptostegia. 



7. Textilaridea. 



8. Cassidulinidea. 



B. With an exceedingly porous, calcareous test. 



I. Rotalidea. 



C. With a calcareous shell, traversed by a ramified canal-system. 



1 . Polystomellidea. 



2. Nummulitidea. 



With regard to the classification of the Foraminifera, the author may be 

 excused for quoting some remarks on this subject made by Mr Henry 

 Bowman Brady, F.R.S., one of the highest living authorities on this group 

 of organisms ; since they not only have a most important bearing upon the 

 special point in question, but forcibly express the principles which should 

 guide the philosophic naturalist in his systematic treatment of all such vari- 

 able forms of life:* "A purely artificial classification is ill adapted to 

 the conditions presented by a class of organisms like the Foraminifera, 

 largely made up of groups of which the modifications run in parallel lines. 

 This ' isomorphism,' demonstrated chiefly by the labours of Messrs Parker 

 and Jones; whilst it is the source of most of the difficulties the systematist 

 has to contend with, is, at the same time, the key to the natural history of 

 the order. It exists not merely between a single series, in one of the 



* The remarks here quoted are taken from the introduction to Mr 

 Brady's admirable ' Monograph of the Carboniferous Foraminifera of 

 Great Britain.' 



