!^2 Ihe Irish Naturalist. [July, 



2. Number of rows of cortical tubes twice as many as of leaves 

 of corresponding node : Dip/ostie/ur, A. Br. 



* Chief or middle or primary rows stronger developed, 

 spines on edges of cortex : Tylacantha. 



(a.) Dioecious, - - - - 28. C. ceratophylla, Wallr., 



or C. to/nentosa, Linn. 

 {b.) Monoecious. 



a. Oospore or nucule with chalky involucre, plant also 



always more or less iucrusted. 

 * Oospore black. 



** Spines of cortex absent or only slightly developed, then 

 always solitary. 

 Oospore (nucule) with spinules (thornlets) ; 6S0 p. 1/37) 

 inch) long at most ; leaflets scarcely developed ; 011 

 the back of the leaf. 

 *** Leaves of normal length, at any rate never conspicuously 

 short, with several cortexed or at least fertile leaf 

 nodes. 30. C. eontraria, Kiitz. 



** Spines of cortex strongly developed, solitary and also 

 always some tufted, sometimes the latter only 

 present ; 

 Oospore with or without spinules ; leaflets fairly uniformly 

 au*d strongly developed round the leaf. 

 *** Oospore more than 700 \i. (1/36 inch) long, with 10-12 

 strong bands 32. C. po/yaeant/ia, Braun. 



* Oospore brown (very rarely almost black), more than 

 700 fi. long (1/36 inch), leaflets on the back of leaf 

 very short. Spines mostly strongly developed, 

 sometimes tufted, more rarely scattered, but then 



still long and strong. 



33. \C. papulosa, Kiitz., or 



C. intermedia, A. Br.] 



/3. Oospore without chalky envelope, plant not iucrusted, 



Oospore more than 700 ji (1/33 inch) long, black with 



strong spinules. 



[34. C. baltica.~] 



f Primary or middle rows more or less raised above the 



secondary or intervening rows, more rarely both 



almost equally developed. 



Thorns (or papillae or the isodiametric cells, in forms 

 which develop neither thorns nor papillce) in the 

 grooves or furrows, often quite absent from the 

 secondary rows : Aulacantluv, A. Br. 



Stem and leaves completely cortexed except one or a 

 few of the no longer fertile leaf-segments. 



Antheridia and oogonia together. 

 ■ The nodal cells of the cortical tubes develop either no 

 pnpilke or spines or these remain small and relatively 

 thick, always solitary. 



