BY G. I. PLAYFAIR. 477 



Var. ALTius, n.var. (Pl.xiii., f.4rt). 



Forma semicellulis basin versus quadratis; angulis basalibus 

 rectis; lateribus e basi parallelis suisum ad apices convergen- 

 tibus; apicibus late-truncatis; angulis lateribus et superioribus 

 levigatis. Long.60; lat.40; ap.20; isth.8//. 



Guildford(89). Cum priori. 



Var. QUADRIGEMINATUM Playf., I.e., p.614. (Pl.xiii., f.l). 



Long.45-52; lat.34-38; crass. 25; ap. fronte 15-20; latere 14/x. 



Guildford(60), Fairfieid(79). Cum priori rarius. 



With its four nodules at the apex, this has the appearance of 



being a collateral type. It is, I think, certain, however, that it 



resolves itself into var. nodulatum. Tlie form of var. Camhrensey 



supra, is practicall}' a forma minor of this, as it must have four 



nodules. 



Var. NOTATUM, n.var. (Pl.xiii., f.2). 



Semicellulje altiores, magis quadratae; lateribus parallelis; 

 apicibus leviter arcuatis: angulis inferioribus ut in Cos. repando 

 Nord. notatis. Long.50-51; lat.40-42; crass. 24-3 1/x. 



Collector. 



This has the same markings under the basal angles as Cos. 

 repanduin ; they foreshadow the accentuated angles and pointed, 

 end-view of var. nodulatum. 



Var. REPANDUM(Nord.). (Pl.xiii., f.l 2). 

 Forma lateribus perfecte rectis. Long.43-50; lat. 30-40; crass. 



00 



J.2fi. 



Collector. 



Cf. Nord., Frw. Alg. N. Z., p.5S, PI. 6, f.l4. This form pro- 

 bably develops into var. nodulatum; while Nordstedt's form, 

 with hollow sides, grows into var. denlatum mihi. 



Var. ANGUSTius(Nord.), I.e., p. 58, T.vi., f. 15, 16. 



Long.32-33; lat.24; isth.8;i. 

 Collector. 



