14 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



A. GrevillH (Hass.) Rab., Fig. 10. Masses of this jelly- 

 like plant frequently reach 2mm. in diameter. 



Chroococcus Nag. Blue-green cells, spherical, or an- 

 gular from mutual pressure, gathered into small families with- 

 out a distinct tegument. The cells, which are less numerous and 

 more simple than in Glccocapsa, divide alternately in three 

 directions. 



C. cohccrcns (Breb.)Nag., Fig. 210. 



FAMILY II. CHAMJESIPHONIACE^E. 



Not represented in the United States. 



ORDER II. HORMOGONE/E. 



This order contains all the filamentous Myxophyceae. 

 The filaments usually consist of a single row of naked or 

 sheathed cells, but in some genera there are two or more rows 

 in a single sheath. Heterocysts are abundant in some of the 

 genera. The filaments are often branched or provided with a 

 false branch system due to the growth of a number of filaments 

 in close apposition at the base. Asexual reproduction is by 

 hormogones or, more rarely, by spores. The filaments or 

 trichomes are usually cylindrical with blunt or narrowed ex- 

 tremities, but some genera show a gradual attenuation, either 

 from the base to the apex, or from the centre toward each end. 



This order includes two sub-orders. 



Sub-order i. TRICHOPHORE.E. Trichomes conspicu- 

 ously attenuated towards one or both extremities, which are 

 generally hairy. 



Sub-order ii. PSILONEMATEyE. Trichomes cylindrical, 

 though sometimes narrowed at the extremities. 



SUB-ORDER I. TRICHOPHORE.E. 



A small group with the filaments always attenuated, either 

 toward one end or from the middle to both extremities, and 

 always sheathed. Some genera are provided with heterocysts. 

 There is an asexual reproduction by means of hormogones, but 

 in GJccotrichia the basal cells next the heterocysts develop 

 spores. The threads frequently show hair-like projections 

 from their sides. 



