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



quamque depressioDem majorem 6 depressionibus minoribus ; semicellulse apicibus 

 depressionibus minoribus obsessse ; massa chlorophyllacea semicellularum laminis 

 lateralibus 5. 

 Long. 74-78 ^t ; lat. 49-51 ^ ; lat. istlim. 35-37 ^n. 

 Nos. and 1. 



This Cosmarium differs from all allied ones in the fact that the granulate appearance is 

 produced by depressions of the membrane, and not by elevations. These depressions are 

 of two sizes, and they are quincuncially arranged in such a manner that between each 

 of the larger depressions, in either a vertical or diagonal line, there are tivo smaller 

 ones ; thus the smaller ones are arranged in hexagons around the larger. The hexagons 

 formed by the larger depressions always have two of their opposite sides horizontal. 



112. Cosmarium, sp. (PL YIII. fig. 15.) C. parvum If-plo longius quam latum, pro- 

 funde constrictum, sinu aperto et obtuso ; semicellulse subhemisphsericae, angulis 

 inferioribus rotundatis ; a vertice visse late subellipticse et zygomorphicse ; a latere 

 visas obovatae et lateribus divergentibus rectis inaequalibus, apicibus obliquis. 



Long. 28 ^t ; lat. 17 ^u ; lat. isthm. 7 n ; crass. 14 /u. 



No. 8. 



Only one example of this species was seen. 



113. Cosmarium moniliforme, Ralfs, Brit. Desmid. p. 107, tab. xvii. fig. 6. 

 Long. 25 /i ; lat. 14'5 fx ; lat. isthm. 4 ^u. (PI. IX. fig. 30.) 



Ko. 1. 



Var. PUNCTATUM, Lagerh. Ueber ein. Alg. aus Cuba, Jamaica und Puerto-Itico, j). 197. 

 Long. 24 n ; lat. 14 ^ ; lat. isthm. 3-5 ^. (PL IX. fig. 31.) 

 No. 0. 



114. Cosmarium goniodes, nov. sp. (PL VIII. fig. 8.) C. parvum, duplo longius quam 

 latum, paullo constrictum, sinu aperto ; semicellulse subcuneato-quadratse, lateribus 

 rectis, angulis superioribus truncatis, apicibus levissime concavis ; a vertice visa^ 

 circulares ; membrana glabra. 



Long. 16-20 ^t ; lat. 8-95 ft; lat. isthm. 6 /u. 

 No. 3. 



The nearest allies to this species are C. exiguum, Archer, C. j^setidexigimm, Racib., 

 and C. moniliforme, Ralfs. 



115. Cosmarium contractum, Kirchn. Alg. Schles. p. 147. 



Long. 31 iu ; lat. 23 ^ ; lat. isthm. 57 fi ; crass. 14-5. (PL VIII. fig. 5.) 

 No. 0. 



116. Cosmarium ayersum, nov. sp. (PL VIII. figs. 6-7.) C. parvum, IJ-plo longius 

 quam latum, profunde constrictum, sinu apertissimo ; semicellulse obsemicirculares 



