Bourrelly: Loricae & Cysts in Chrysophyceae 



427 



Derepyxis (figure 6), monads with two flagella and the Lepochromiilina (figure 

 8), with single flagellum. We mention also, the extraordinary Chrysopyxis of 

 which the cellulose lorica, in the form of a saddle, attaches itself to the fila- 

 mentary algae by a thin cellulose cord which completely entwines the support- 

 ing algae. ^ 



Alongside of the Chrysophyceae with loricae of homogeneous structure, we 

 may place the species of the family of the Synuraceae in which the lorica is 

 replaced by a covering of siliceous scales (figure 7). 



Figure 8. Loricae and cysts (after Bourrelly). 1: Dinobryon divergens, lorica and cyto- 

 plasm; 2: Lepochromulina calyx, lorica and cytoplasm; 3-5: IleterocltromuUna vhipara var. 

 minor, building of cyst; 6: Dinobryon niriculus, lorica and division; 7: c\st of Chrysostomacea 

 Outesia; 8: cyst of Ouiesia; 10: cyst of Clericia; 11: cyst of Deflandreia (?). bb: mouth-band; 

 Cm: muciferous bodies; cv-vc: contractile vacuole; cy: cytoplasm; ep: epipode (contractile 

 thread); /-/2: flagella; gg: oil-drop; k: membrane of cyst; /: leucosin; Ic: cellulosic lorica; n: 

 nucleus; p: parabasal body; pi: chromatophore; s-s s2: stigma; sy: symbionts. 



The scales arranged in helicoidal series, such as these of the Dinobryon 

 utriculus (figure 1*), have been the subject of fine studies in electronic mi- 

 croscopy. 



The systematization of the genus Mallomonas (about 100 species) of the genus 

 Synura (12 species) is almost solely based upon the form of the scales and of the 

 bristles which adorn them. The observation of a single siliceous scale is some- 

 times enough to permit the identification of the species. This is not the case 

 with the true lorica, in which we have a convergence of form to such an extent 

 that it is impossible in certain instances to decide from the study of an empty 



* The scales of Dinobryon utriculus are not siliceous, but pecto-cellulosic. 



