236 ARCHER, ON DESMIDIACEA. 



view about one third longer than broad, rough all over with 

 minute, scattered, somewhat depressed pearly granules, which 

 give a minutely denticulate appearance to the margin, deeply 

 constricted at the middle, the constriction forming a gradually 

 widening notch at each side, rounded below ; segments, in 

 front view, broadly elliptic, in side view, suborbicular, con- 

 nected by a rather narrow isthmus, forming a short neck ; 

 end view, broadly elliptic. (Sporangium, after a figure by 

 Professor De Bary of an undescribed species supposed to be 

 the present : orbicular, beset with somewhat elongate, conical, 

 blunt spines.) 



Measurements: Length of frond, ^ B th ; breadth of frond, 

 y joih of an inch. 



Plate XI. — Fig. 8, front view; Pig. 9, end view. 



Affinities : The granulated surface and compressed frond in 

 this species forbid its being mistaken for any of those in 

 which the surface is smooth, or the end view circular. Of 

 those species with which it agrees in the characters first in- 

 dicated, it is about the most minute, and I believe it is other- 

 wise amply distinguished from them by its elliptic segments 

 in front view. It perhaps most approaches C. margaritiferum 

 (Menegh.), but, besides its smaller size, it differs from that 

 species and C. latum (Breb.) in not having reniform or semi- 

 orbicular segments, as well as in the constriction being not a 

 linear, but a wide notch. The same characters distinguish 

 it from ft Brebissonii (Menegh.), as well as the pearly 

 granules being minute and closely scattered, not rather 

 widely distributed and conic. From C. tetraopfithalnmm 

 (Breb.) it also differs in the same characters, as well as in 

 that of the superficial granules, which in that species are 

 broad, giving the margin a somewhat undulate or crcnate, 

 rather than a minutely denticulate, appearance. Prom ft 

 Broomei (Thwaites) and ft biretum (Breb.) it differs, besides 

 other characters, in its elliptic, not quadrilateral or angular, 

 segments. Prom C. preemorsum (Breo.)j ft notabile (iircb.), 

 and ft Botrytis (Menegh.), as well as ft protractum (Nag.), 

 C. gemmiferum (Breb.), and C. Turpinii (Br€b.), it differs in 

 having rounded, not truncate, ends, and from all the species 

 just named in the central constriction, not forming a linear 

 but a wide notch. 



It is at once distinguished from C. orbiculatum ( Balfe), with 

 which it agrees in the constriction not forming a linear notch, 

 by the segments being elliptic, not spherical, and the cud 

 view not circular; besides the pearly granules being minute 



