Introduction to Animal Morphology. 55 



the primary spiral. i^th. Nummulitidx finely perforate, 

 with a special septal plane differentiated from the rest 

 of the shell, without the ordinary tubular structure. Each 

 chamber wall is complete in itself, ex. Archceodiscus, Poly- 

 stomella,* Nummulites, Orbitoides, Fusulina ? 



Probably these are not true families, as outward characters 

 are variable, and passage forms are numerous.! 



CLASS 4. FLAGELLATA (Ehrcnbcrg}. Nucleated plas- 

 tides, each moving by a long, permanent, whip-like 

 process; reproducing by fission or gemmation ; motion 

 is by swimming or rolling (Doxococcus). 



They are divisible into two orders: ist. Monadina 

 minute, vacuolated forms, with no differentiated ectosarc, and 

 simple flagella. These comprise two families: ist. Mo- 

 nadidcc having a constant shape ; reproducing by longitu- 

 dinal or transverse fission ; with one flagellum (Monas), or two 

 (Glenomorum) ; sometimes with a red speck (Microglena) ; 

 some are pear-shaped with a thick tail (Bodo), or the monads 

 may be in clusters, each with two flagella (Uvella). In 

 Anthophysa they are stalked, and have a contractile vesicle, 

 and in Polytoma the clusters of monadiform spheres produced 

 by incomplete division are within a hyaline cuticle. There 

 may be an oval (Cryptomonas) or a flask-like lorica 

 (Lagenella). Trichomonas has a few cilia as well as two 

 flagella. 



.in. 2nd. Astasiidoe, with no lorica and a variable shape. 

 Colacium is parasitic on crustaceans ; others arc' free, with no 

 peck (Astasia), or with one (Euglena) or two (Diselmis). 

 i is rounded, tapering to the flagellum, with colour- 

 less granules and vaeuoles within a thin cell-wall. There 

 may r.il (Pulyselmis), or two equal (Zygosclmis) or 



Sometimes | a family Polystomd' 



t D'Orbigny's classification is embodied in a note on a former page : it 

 takes for its basis the modes of budding. SJiul: 1 them on the 



same ground into Soroidea, Rhabdoidca, and II 



