DY G. I. PLAYFAIK. 



817 



Milii incertae sedis. 



Genus Exuviella Ehr . 



Exuviella lima (Ehr.) Scbutt . (Text-fig. 18 a, b) . 



Membrana levis vel punctata. 



Long. 30-33, lat. 21-26, crass. 10-1-15 ^ 



Canley Vale (94); Fairfield (112); Botanic Gardens (125); 

 Centennial Park (133). 



Syn. Diuopyxis laevis Stein; Xanthocliscus Lauterbachi Sche- 

 wiakowski. Found in freshwater only in Australia; a marine 



d 



Text-fig. 18. 

 [(a) Exuviella Lima (Ehr.) Schutt, (b) side view .(x 6(30) ; (r) var. 

 major, n. var., (d) side view, (x 500). 



organism, apparently, elsewhere. Cf. Stein, Naturg. d. Flagell., 

 ii., T. 1, f . 27-33 ; Schutt, Gymnodiniaceae , p. 8, fig. 9 . 



Var. scrobiculata, n. var. 



Membrana erasse scrobiculata; areolata etiam. Dimensiones 

 ut m forma typiea. Cum priori. 



The type, as Stein's synonym shows, has a clear membrane, 

 but specimens may be found finely punctate. With them how- 

 ever are often found others with every degree of scrobiculation, 

 even to being areolate. These scrobiculae are on the inner side 

 of the membrane. The test consists of dorsal and ventral valves 

 merely adhering to one another longitudinally by the rims, not 

 overlapping as in the Diatomaceae. The dorsal valve is simply 

 slightly flattened at the end while the ventral one is deeply 

 notched at the same place. Along the suture in each valve is 

 a series of markings resembling the carinal dots in the diato- 

 maceous genus Nitzschia, but these are not always present. The 

 valves in side view almost always appear somewhat curved. I 

 have noted a smaller size than those given above — long. 25, lat. 

 ?, crass. 8 fj.. 



