1S90.] MICROSCOPICAL JOURNAL. 14:7 



Of this beautiful species, two forms were noticed along with the type. 

 One, a nine-rayed form, was seen several times ; the other, a very long 

 and slender-armed one, measured 145 //. across the arms. Cooke and 

 Wolle describe the end view as 7 (rarely 6 or 8) rayed ; the forms from 

 Capel Curig are almost all S-rayed. 



Fig. 16. — Staurastruni cyrtoceruin Br^b., forma tetragona. (Forma 

 a vertice tetragona.) 



Fig. 17. — Docidlum elongatum nov. sp. (D. quadragies longius 

 quam latum, ad utrumque polum sensim attenuatum, apicibus trunca- 

 tis, medio non inflato.) 



Frond about forty times as long as broad, the straight sides gradually 

 tapering from the uninflated base of each semicell to the truncate apex. 



Fig. 18. — Cos?narium orblculatutn Ralfs. The figure ■ is given 

 merely for comparison with Fig. 19. 



Fig. 19. — Cos7nariu?n isthfuiuin nov. sp. 



This form is the same as C. excavatum Nord, var. dziplo-major 

 Lund., as described and figured by Wolle. As the author does not l)e- 

 lieve this species to be a variety of C. excavatum^ he proposes the above 

 name. A. W. Bennett, however, does not adopt the name, but believes 

 the form identical with C. orbiculatuni^ the width of the isthmus being 

 merely an indication of early stage of division. 



Fig. 20. — Staurastruni spifilferzim nov. sp. (S. parvum, semi- 

 cellulis ellipticis cum octo spinis (circa) ad marginem semicellulie sin- 

 guhe, a vertice triangulare cum spinis novem, lateribus leviter conca- 

 vis.) 



Segments elliptic, with about eight spines in the periphery of each 

 segment; end view triangular, sides very slightly concave, showing 

 two spines between each apical one. 



Fig. 21. — Xanthidiuni crlstatuni Breb. var. spinuliferu7n nov. 

 var. (Var. cum quattuor vel quinque spinis parvioribus additis inie- 

 qualiter ordinatis intra marginem semicellula3 singular.) 



This has four or five additional spines, rather unequally disposed 

 just within the margin of the front view of each semicell. 



Fig. 22. — Staurastrum controvcrszt?n Breb. The figure is given in 

 order to show a variety of this variable species. 



Fig. 33. — Closteriuni strlolatum Ehrb., forma recta. (Non cur- 

 vata, rectissima.) 



This difibrs from the type in having no curvature ; several examples 

 were seen, and were turned over and over. 



Fig. 24. — Penluni spirostriolatum Bark. As this species appears 

 to vary in different localities, some figures are given. This variability 

 has been noticed from Maine, N. Ireland, Scandale in 'the lake district, 

 and Glen Shee and Craig and Lochan in Scotland. The parallel 

 striae can often be seen on both the upper and under surfaces of the 

 empty cylindrical frond, and then they appear as if they crossed each 

 other. 



Fig. 25. — Cosmarium tetraophthaltnum var. subrotundum nov. var. 

 Newborough Warren. (Var. sinu apertissimo semicellulis subrotundis 

 facto.) 



This differs from the type in the open sinus caused by the subrotund 

 semicells. 



Fig. 26. — Euastruni verrucosum Ehrb. This is a variety with more 

 gaping sinus than usual and a subrectangular polar lobe. 



