ZYGNEMACEJE. 77 



In certain of the species of this genus the zygospores are produced in 

 the conjugating canal, and in other species in one or other of the con- 

 jugating cells. This fact is taken advantage of in the following arrange- 

 ment : 



A. Zygospores produced in conjugating canal. 



* Sporoderm scrobiculate. 



1. Zygnema pectinatum, Ag. 



** Sporoderm even. 



2. Zygnema Ralfsii, Kutz. 



3. Zygnema parvulum, Kutz. 



B. Zygospores produced in one or other of the conjugating cells. 



* Sporoderm punctate. 



4. Zygnema cruciatum (Vauch.). 



5. Zygnema stellinum (Vauch.). 



6. Zygnema Vaucherii, Ag. 



7. Zygnema anomalum (Hass.). 



** Sporoderm even. 



8. Zygnema leiospermum, DeBary. 



9. Zygnema insigne, Kutz. 



A. Zygospores produced in conjugating canal. 

 Zygnema pectinatum. Ag. Syst. p. 78. 



Sterile cells 1-2 times as long as broad. 



Zygospore globose or broadly elliptic, dark olive, scrobicu- 

 late, formed in the canal of conjugation. 



SIZE. Cells -03-'035 mm. diam. (sometimes less), zygospore 

 04 mm. diam. 



DeBary Conj. p. 77, t. 1, f. 15; 19, t. 8, f. 13. Gray 

 Arr. i. 1296. 



Conjagata pectinata, Vauch. Conj. p. 77, t. 7, f. 4. 



Conferva bipunctata, Eng. Bot. t. 1610. 



Conferva decussata, Dillw. Conf. Syn. p. 5, (?) 



Zygogonium pectinatum^ Rabh. Alg. iii., 252. Kirsch. Alg. 

 Schl. p. 126. 



Tyndaridea conspicua, Hass. Alg. t. 39, f. 1, 2, Ann. Nat. 

 Hist, xii., 187, t. 7, f. 17. 



Tyndaridea immersa, Hass. Alg. t. 39, f. 3. Ann. Nat. Hist, 

 xii. 188, t. 7, f. 19. 



Tyndaridea decussata, Hass. Alg. t. 39, f. 6. Ann. N. Hist, 

 xii., 188, t. 7, f. 18. 



Zygogonium conspicuum, Kutz. Tab. v. t. 12, f. 2. 

 .Zygogonium immersum, Kutz. Tab. v. t. 12, f. 5. 



Zygogonium decussatum, Kutz. Tab. v. t. 11, f. 4. 



Tyndaridea pectinata, Eng. Fl. v. p. 361 ; Eng. Bot. ii. t. 

 2597, Harv. Man. 142 ; Mack. Hib. 231. 



Zygnema bipunctatum, Grev. Fl. Ed. 320 ; Fl. Devon, ii. 50. 



In still waters. 



As noted above, we include here three of Hassall's species of Tynda- 

 ridea. Kirschner does the same, with the addition of Kutzing's Z ano- 



