62 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [BuU. 



Halteria Duj. 



Inflexible, spherical. Upon the anterior end an adoral 

 ciliated zone which extends from the right over the dorsal 

 surface to the left, and then leads to a ventral mouth. 

 The part of the body surrounded by the spiral zone 

 slightly protruding. Near the middle of the body is a 

 crown of simple long bristles, but otherwise it is without 

 body cilia. Spherical nucleus ; contractile vacuole near 

 the left side. 

 H. grandinella Miill., Fig. 227. Fig. 2270 shows the 

 same species in process of division. Another view of 

 probably the same animal is shown in Fig. 230. 

 Strombidium CI. & L. 



Like Halteria, but without the bristles. The part of 

 the body surrounded by the ciliated zone is protrusible; 

 frequently with trichocysts. Upon the ventral surface a 

 few single cilia or groups of cilia ; colorless or yellowish ; 

 nucleus and contractile vacuole as in Halteria. 

 Str. sp. ( ?), Fig. 229. 



ORDER PERITRICHA. 

 Key to Genera. 



1. No lorica 2 



With lorica 8 



2. No stalk 3 



With stalk; simple or branched, with or without an 

 axial fibre 5 



3. Posterior ciliated ring persistent; the disk-shaped 



posterior end with a chitinous ring Trichodina* 



Posterior ciliated ring found only in the swimming 



stage 4 



Posterior ciliated ring wholly absent; never at- 

 tached; posterior end with two bristles. . . .Astylosoon 



4. Posterior end elongated; usually attached Scyphidia 



Posterior end not elongated ; body conical ; attached 



or free; when contracted acorn-shaped Gerda 



5. Stalk branched 6 



Stalk simple 7 



6. Stalk retractile; each zooid contracting separately. . 



Carchesium^ 



