BY G. I. PLAYFAIR. 325 



form under consideration somewhat resembles Cos. sexangulare 

 f. minima Nord. It is of the same size, but the apices are nar- 

 rower^ and the sides not at all retuse; the lateral angles also 

 opposite the centre of the semicell, higher rather than lower. 

 Gf. Nordstedt, N.Z., p.60, PL vii., f.26, 27: W. k G. S. West, 

 Monog. iii., p.82, PI. 72, f.4, 5. It should be remembered that 

 Cos sexangulare Lund., and Cos. sulcatum Nord., are themselves, 

 biologically, forms of Cos. rectangulare Grun., cf. Polym. and 

 Life-hist, p.481-2, PI. xiii, f.20-22. All the above forms, with 

 Cos. red. var. cyclopeuin Playf . (30 x 24, basis 16, isth. 5/x)., I.e., 

 PL xiii., f.7, were found together in the same gathering; compare 

 my remarks. I.e., p. 475. 



Cos. PSEUDOPROTUBERANS var. AUSTRALE, n.var. (PL xli., f.l7.) 



Forma major validor. Semicellulse papillis binis infra apices 

 a fronte non cernendis; a vertice ellipticae apicibus acuminatis, 

 utrinque in medio papillis binis instructse. 



Long. 50, lat. 42, basis c. 28, isth. 9 //. 



Lismore(185). 



With the type, 34 x 28, isth. 6 /x. This large form is not at 

 all uncommon round Sydney, in shallow waters where Xan. 

 hastiferum is to be found. It is practically a spineless form of 

 the latter. Cos. pseudo2)rotubera7is forma, Borge, Austral. Siissw. 

 Alg., p. 23, T.3, f.39, is certainly a form of Cos. rectangulare, 

 probably near to, if not identical with, var. austi-ale, Playf., 

 Polym. and Life-hist., p.480, PL xiii., f.l4, 15. 



Cos. MONILIFORME var. SUBQUADRATUM, n.var. (PL xlL.f. 18.) 



Semicellulse subquadratse ubique rotundatse, apicibus paullo 

 deplanatis; a vertice visse, orbiculatse. Membrana glabra. 



Long. 30, lat. 18, isth. 3 /x. 



Lismore (185). 



One semicell was very slightly produced and angulate at each 

 side, a little above the centre. This indicates a connection with 

 Cos. pseudoprotuherans. Var. subquadrattwi is intermediate 

 between Cos. moniliforyne and Jacobsen's form {Cos. Jacobsenii 

 Roy). It shows that Nordstedt was right in making the one a 

 f. elliptica of the other (Norges Desm., p. 22). W. & G. S. West, 



