The Scottish Naturalist. 39 



S. CTMearii Archer. — M. 



S. cuspidaium Breb. — T. 



S. pterosporum Lundell. — M. 



S. Avicula Breb. — T. 



S. margaritaceum Ehr. — L.S. ; T. ; M. 



S. dilatatum Ehr. — M. 



S. Brebissonii Archer. — L.S. 



.>. crista turn Nseg. — T. 



S. Maamense Archer {S. pseudo-crenatum Lundell). — T. 



S. scabrum Breb. — M. ; T. 



6". spinosum Ralfs. — M. 



S. Beinsckii, n. sp. {Reinsch " Contrib. Alg. et Fung.,'''' Tab. 



XVII., f. s.)— T. ; M. 

 S. polymorphum Breb. — T. ; M. 

 S. cyrtocerum Ralfs. — T. 

 S. paradoxum Megen. — M. 

 S. tetracerum Kg. — T. ; M. 

 S. pileolatuni. — T. 

 S. Arctiscon Ehr. — T. 

 Tetme?7iorus Brebissonii Menegh. — L. S. ; T. ; M. Var. 



£.— M. ; T. 

 T. granulatus Breb. — L.S. ; M. ; T. 

 T. /^Kg.-T.; M. 

 Closterium obtusion Breb. — S. ; M. 

 C. didymotocum Corda. — M. 

 C. cornu Ehr. — M. 

 C. calosporum Wittrock. — T. 

 C. Venus Kg.— M. 

 C. attenuatum Ehr. — M. 

 Benium Digitus Ehr. — T. ; M. 

 B. oblongum de Bary. — T. ; M. 

 B. Navicula Breb.— L.S. ; M. 

 B. didymocarpum Lundell. — T. 

 B. polymorphum Perty. — T. ; M. 



B. Iruncatum Ralfs. — T. ; M. 

 Cylindrocystis Brebissonii Menegh. — S. ; T. ; M. 



C. crassa de Bary. — T. ; M. 



Docidium minutum Ralfs {Ben. minutum de Bary). — T. ; M. 



D. Ehrenbergii Ralfs. — T. ; M. 

 D. Sceptrum Kg. — M. 



Some years ago Mr. Archer sent me this curious and very distinct species 

 from the west of Ireland, as being possibly the Docidium Sceptrum of 

 Kiitzing. It may be, but I fear it is impossible to identify his species with any 

 certainty from his description in " Species Algarum, p. 168. From the swollen 

 base the slender semi-cell tapers gradually to a sharply truncate apex, which is 

 terminated by four small, acute, conical teeth. Surface smooth. Length of 

 semicell, which has a slightly projecting ring at the base, y^ in. ; breadth of 

 basal swelling, tt^o m - '■> do. immediately beyond, ^ Vo ^ n> '■> do. at apex, 

 ^55 in. These measures are approximate only, the gathering containing this 

 species not being in good condition by the time it came into my hands. 



