COSMARIIDI. 51 



been found amongst various hepatics on trees (at 4500 ft.) in a 

 matrix consisting mostly of subaerial blue-green Alo-a3. 



It varies much in size and the forms have been arranged in 

 three groups as follows : 



1. Forma minor Xordst. Length 14-15'5 ft ; breadth 



11-13 fJL. 



2. Forma media Nordst. Length 18'5 ^ ; breadth 13 fj.. 



3. Forma major Xordst. Length 23-27 /LI ; breadth 18-24 it. 

 (PL LXXII, fig. 39). 



Intermediate sizes occur between these three forms, and the 

 full range of measurements is given after the description. 



C. obliquum is a well-marked species by reason of its slight 

 constriction and the zygomorphic character of the vertical 

 view. The side view is also characteristic owing to the 

 truncate apices and the inequality of the faint constriction on 

 the two sides. It stands nearest to C. Norimbergense Reinsch, 

 to which species it has been proposed to refer it as " forma 

 obliqua" We think,, however, that the characters of C. 

 obliquum are such as to warrant complete separation as a 

 species. It is less deeply constricted than C. Norimbergense, 

 and the characters of its side and vertical views are peculiar. 



Forma minima West, (PL LXIX, figs. 22, 23.) 



C. obliquum forma minima West, Alg\ Engl. Lake Distr. 1892, p. 726, t. 

 9, f. 15. 



Cells minute and proportionately longer than in the 



type- 

 Length 11-14 /i ; breadth 8-9 JJL ; breadth of isthmus 



4*2-5 ja; thickness 4'4-6*5 JJL. 



EXGLAXD. Helvellyn and Pike of Bliscoe, West- 

 moreland ! 



Geor/r. Distribution. Xorway. 



Var. trigonum West. (PL LXIX, fig. 24.) 



C. obliquum var. trigonum West, Alg. W. Ireland,, 1892, p. 149, t. 24, f. 13. 



A small variety with the semicells from the vertical 

 view trigonal, sides almost straight, angles rounded. 



Length 17*5 /x; breadth 14 ^ ; breadth of isthmus 

 -8'5 JJL. 



IKELAXD. Carrantuohill, Kerry ! 



