376 CAMPYLODISCUS. 



Analysis of the Diatomaceous Genus Campylodiscus," London, 1891. Mr. 

 Deby admits 92 species into the genus, and divides them into 5 sections, as 

 follows : (1.), The Raphidaa ; (11,), the Vagae ; (in.), the Hyalinse ; (iv.), the 

 Striatae; and (v.), the Punctata?. We shall adopt Mr. Deby's sections and 

 analysis. 



SECTION I. Raphidce. Valves furnished with a narrow hyaline 

 space, or longitudinal line (Raphe). 



f Area limited internally by a distinct line, being the termination of the costae ; 



discs without a trapezoidal inscribed line . . . C. Hodgsonii. 



r . j 1 f Raphe reduced to a mathematical line . . C. Ralfsii. 



Area not limited by ' 



Raphe enlarged, distinct. , . C decorus. 



C. Hodgsonii W. Sm. (S.B.D., i., p. 29, pi. 6, f. 53* ; Deby, pi. 

 1, f. 7) plate 32, fig. 868. 



Valve appearing irregularly circular, furnished with a crown of radiant 

 costae, short, confluent on the interior side in a circular line ; costae 3 or 3-5 

 in 1 c.d.m. Median hyaline space, narrow, lanceolate, bordered on each side 

 by transverse rows of coarse beads. Diameter, about 18 c.d.m. 



Marine. England (Hodgson, Norman, W. Sm.), Ireland (O'Meara), France (Brebisson). 



C. Ralfsii W. Sm. (S.B.D., i., p. 30, pi. 30, f. 257, ; Deby, pi. 

 2, f. 18*). plate 32, fig. 869. 



Valve small, almost regularly circular, showing narrow costae extending up 

 to the raphe, which appears in the form of a mathematical line. Costae on 

 the margin of the valve, 4 in 1 c.d.m. Diameter, 4 to 4'8 c.d.m. 



Marine. England (W. Sm., Kitton), Ireland (O'Meara), Coasts of France (Brebisson), 

 Bahnsie (Eagerstedt). 



C. decorus Breb. (Diat. Cherb., f. 2 ; h.v.h. Atl., pi. 75, f. 3*), 

 plate 14, fig. 596. 



Differs from C. Ralfsii by the rather broad median area and by its size, 

 which is larger. 



Marine. Escant (H.V.H.), England, (Norman). 



forma minima ? (H.V.H. Atl., pi. 77, f. 2*), plate 14, fig. 597. 

 Under the name of C. parvulus. Antwerp (Scheldt). 



