238 MESSES. W. WEST AND G. S. WEST ON 



The plant which came under our observation was evidently the same species as that 

 figured by Wolle, though he says *' membrane smooth " ; all those noticed by us were 

 minutely scrobiculate. C. fumida, E. Gay (in Rev. Sc. Nat. ser. III. iii. (1883) p. 228, 

 t. 1. fig. 1), is a very different plant, with no constriction, no angularity, and a smooth 

 membrane. 



Genus Tetmemoeus, Ealfs. 



35. T. GRANULATUS, Ralfs, Brit. Desm. p. 146, t. 24. fig. 3. 



Var. ATTENUATUS, West, in Journ. Linn Soc. (Bot.) xxix. (1892) p. 132, pi. 20. fig. 7. 



Long. 303 |i ; lat. ad has. semicell. 42 fx ; lat. isthm. 37 ^ ; lat. ad apic. 21-22 fx ; lat. 

 subapic. 21-23 /n. 



This is a larger form than the Irish plant, but otherwise precisely the same. The figure 

 published of the above was not a good one and did not show the attenuation sufficiently. 



Genus Micrasterias, Agardh. 



36. M. ARCUATA, Bail, in Smithson. Contrib. to Knowl. 1850, p. 37, t. 1. fig. 6 ; Wolle, 



Desm. U.S. p. 117, pL 38. fig. 5 ; Nordst. in Ofvers. Sv. Vet.-Akad. Forh. (1877) 

 n. 3, p. 22, cum fig. xylogr. ii. 1-2. 



Yar. GRACILIS, nov. var. (PI. XIII. fig. 27.) Var. gracilior, lobis raulto angustioribus, 

 lobo polari processibus subconvergentibus ; apicibus omnibus loborum mucronatis 

 (vide Nordst.). 



Long. 77-81 ^i ; lat. 98-115 ^u ; lat. isthm. 9-10-5 /i. 



Hab. Harvey Lake, Lycoming Co., Pa. 



37. M. PixxATiFiDA, Ralfs, Brit. Desm. p. 77, 1. 10. fig. 3. (Euastrum pinnatifidum, Kuetz. 

 Phycolog. Germ. p. 134.) Zygospora globosa, spinis longis validis attenuatis acutis 

 ornatis, cum papilla obtusa intra basin uniuscujusque spinse. 



Diam. zygosp. sine spin. 44 n, cum spin. 67 n. (PI. XIII. fig. 28.) 

 Porma major, lobis longioribus et tenuioribus. 

 Long. 78 ^i ; lat. 96 ^ ; lat. isthm. 12 n. 

 „ 82-5 ^t; „ 100 iu; „ „ 12-5 m- 

 „ 82-5^; „ 105^; „ „ 12 5 ;it. 

 „ 81 A* ; ,, 106 ju ; „ „ 13 fx. 

 Forma. (PI. XIIL fig. 29.) 

 Long. 54 fx ; lat. 55-62 ,u ; lat. isthm. 12 a*. 

 Hah. Harvey Lake, Lycoming Co., Pa. 



This form had one semicell like var. inflata, Wolle (Desm. U.S. p. 116, pi. 37. 

 fig. 9=var. quadrata, W. B. Turn. Freshw. Alg. of E. India, p. 89, t. 5. fig. 3 ^'), the 

 other semicell being like var. expansa, W. B. Turn, (h c. fig. 3 e), thus showing these are 

 but forms of the same variety. 



38. M. DEPAirpERATA, Nordst. in Vidensk. Meddel. 1869 (1870), p. 222, cum fig.)- 

 Forma major, spinis curvatis ad angulos furcatos, lobo polari breviori ; membrane 

 delicatissime punctata. 



