BY G. I. PLATFAIR. 327 



Cos. AURicuLATUM Reinsch. (PI. xlii., f.4,5.) 



Long. 57, lat. 57, isth. 25, crass. 30 /x. 



Lismore (1 85). 



As I have not access to Reinsch, Contributions, I have had to 

 depend on Turner, Alg. E. Ind., p. 50, PI. vii., f.35, and PI. ix., f.8. 

 The latter is said by the author to be verrucose, but, as his figure 

 does not show any verrucse at the margin, the membrane had 

 probabl}^ the coarse puncta-scrobiculce of Cos. ohsoletum var. 

 Sitvense Gutw. Although Cos. auriculatum is certainly a form 

 of C. ohsoletum, yet, on account of its distinct shape, it is best 

 kept separate. Cos. laticolhim Delp., Desm. subalp., ii., p. 11 6, 

 T.8, f. 20-23, C. erosum Delp.,^.c., P1.8, f. 24-27, and Cos. suberosum 

 Gutw., Alg. in Java coll., p.592, T.38, f.S6, might all be very 

 well arranged as variations of this type. 



Cos. VENUSTUM var. Borgei, nom.nov. (PL xli., f.l9.) 



Forma lateribus e basi plana ad apices truncatos sensim con- 

 vergentibus, valde undulatis; lobis lateralibus nullis; lobo apicali 

 rectangulari, lateribus verticalibus parallelis ; supra medium 

 granulo instructa. 



Long. 30, lat. 22, isth. 4; lob. apic. lat. 12, alt. 6/x. 



Lismore (185). 



Syn., Cos. t^enustuni, forma, Borge, Nordamerik. Siissw. Alg., 

 p 8, tig.5. The latter gives long. 31-32^, lat. 19-191, ap.l3-14i/x 

 as the dimensions. Cf. Cos. venustum, forma, Borge, Austral. 

 Siissw. Alg., p. 23, T.3, f.40, which is somewhat larger, but is a 

 form of this variety. It is the common Australian form. 



Cos. AsKKNASYi var. crateriforme, n.var. (PL xlii., f.6.) 



Semicellulse crateriformes adpressae; sinu lineari extrorsum 

 ampliato; basi plana; angulis basalibus latissime rotundatis, 

 granulis paucis sparsis ornatis; lateribus convexis ad apicem 

 convergentibus; apicibus angustis levissime deplanatis. Infla- 

 tioneC?) supra isthmum. 



Long. 158, lat. 126 /A. 



Lismore (240). 



For the type, see Schmidle, Alg. Sumatra, p.304, T. iv., f.7. 

 This form is very close to the forma in Borge, Austral. Siissw. 



