NO. 4 



ALLEN : PLANKTON DIATOMS 



53 



Comparison of lists from the two coasts taken by the same ex- 

 pedition cannot be made because the November cruise had too few 

 stations in the Gulf and the February-March cruise had too few 

 stations in the ocean. However, the accompanying table helps to 

 show that no essential difference in representation of genera and 

 species of plankton diatoms is observable as yet between Gulf waters 

 and ocean waters. A long series of collections from each would prob- 

 ably show complete identity as to names listed. Indeed, one of the 

 striking features of phytoplankton occurrence in the Gulf as exhibit- 

 ed so far is the likeness of the catches to those obtained in the neigh- 

 boring ocean. This likeness goes so far as to show the same scanty 

 representation of certain species commonly occurring in small num- 

 bers in widely different regions of the ocean. Excellent examples of 

 species commonly noticed but never in large numbers are Platikton- 

 iella sol (Wall.) and Rhizosolenia setigera Btw. 



TABLE I 

 Plankton diatoms of Lower California Peninsula 



Ocean Coast, November, 1935 



Asterionella japonica CI. 



Bacteriastrum sp. 



Biddulphia mobiliensis (Bail.) 



Chaetoceros afRnis Laud. 



atlanticus (Schiitt) 



compressus Laud, 

 concavicornis Mangin. 

 constrictus Gran 

 curvisetus CI. 



debilis CI. 

 decipiens CI. 

 didymus Ehr. 

 eibenii (Grunow) 

 laciniosus Schiitt 

 laeve Leud-Fort. 

 lorenzianus Grun. 

 messanensis Castr. 

 peruvianus Btw. 

 radicans Schiitt 



socialis Laud, 

 spp. 

 tetrastichon CI. 



Gulj Coast, February-March, 1936 



Achnanthes sp. 



Actinoptychus undulatus (Bail.) 

 Asterionella japonica CI. 

 Asteromphalus heptactis (Breb.) 

 Bacteriastrum sp. 



Cerataulina bergonii Perag. 

 Chaetoceros affinis Laud. 



atlanticus (Schiitt) 



coarctatus Laud. 



compressus Laud. 



concavicornis Mangin. 



constrictus Gran 



curvisetus CI. 



danicus CI. 



debilis CI. 



decipiens CI. 



didymus Ehr. 



laciniosus Schiitt 



lorenzianus Grun. 



peruvianus Btw. 

 radicans Schiitt 

 simplex Ost. 

 socialis Laud, 

 spp. 



