4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL.98 



CHLOROPHYCEAE 

 DESMIDIACEAE 



Closterium parvulum Nageli, forma. Text fig. 8. 



These plants are consistently larger (length 150 lk, width 22 (i) than 

 the species as described by West and West (1905, p. 133) and they 

 curve through a greater arc. Krieger (1935, p. 277, pi. 16, fig. 18) 

 in var. majus West admits larger forms and in var. angustum West 

 and West forms as curved ; the present type probably represents yet 

 another minor variant of the species. Rich's African C. prolongum 

 figured on the same plate has more pyrenoids, is somewhat larger 

 and has a greater median swelling, but is otherwise similar. 



Infrequent in the lagoon, particularly in strainings from the 

 Lyngbya masses, Clipperton Island, Mexico (Schmitt 21), Tu'y 21, 

 1938. 



Closterium parvulum, near var. majus West. Text fig. 0. 



These plants were a little more tapering and curved than figured 

 by Krieger (1935, p. 277, pi. 16, fig. iS), but apparently were within 

 his concept of the species and perhaps of the variety. Length 170 /*, 

 width 21.5 fi. 



Frequent in the lagoon, particularly in strainings from the Lyng- 

 bya masses, Clipperton Island, Mexico (Schmitt 21), July 21, 1938. 



Cosmarium clippertonensis, n. sp." Text figs. 1-7. 



Cells small, semicells subtriangular, much wider than long, the end 

 narrowly transversely truncate or slightly refuse, the basal angles 

 obliquely truncate, the sinus closed ; in polar view oval with a promi- 

 nent lateral thickened swelling ; in edge view the semicells subcircu- 

 lar with the same swelling visible ; pyrenoids single in each semicell, 

 the wall smooth. Length 22-24 /*» width 19-20 /x, thickness 13.2 fx, 

 isthmus 4.5 fi. 



These plants seem closest to C. wembaerense forma of Borge 

 ( : 933> P- '4- ft- !> fig- n)- They are not so like his C. scopulorum 

 (1923, p. 12, pi. 1, fig. //), to which he refers, and even less like the 



2 Cosmarium clippertonensis, spec, nov— Cellulae parvae, semicellulis sub- 

 triangulis, latioribus quarn longioribus, transverse truncatis vel retusiusculis ; 

 angulis basalibus obliquiter truncatis; sinu inaperto ; aspectu polari ovalibus, 

 lateraliter incrassatis bullatisque; aspectu laterali semicellulis subglobosis 

 etiamque cum incrassationibus visibilibus ; pyrenoideis in semicellula singulis; 

 membrana laevi. 



