NO. 5 CUPP AND ALLEN: PLANKTON DIATOMS 71 



tl7. Rhizosolenia delicatula CI. (Fig. 12) 



18. Schroderella delicatula (Perag.) Pav. (ocean only) 



19. Stephanop)Tcis turris (Grev. and Am.) Ralfs 



(and subtropical) (Fig. 1) 



20. Thalassiosira rotula Meun. (Fig. 4) 



*21. Thalassiothrix mediterranea Pav. (given as T. heteromorpha Karst. 

 by Allen, 1937) 



TYCHOPELAGIC 



1. Actinoptychus undulatus (Bail.) Ralfs 



2. Licmophora abbreviata Agardh 



3. species 



4. Pleurosigma species 



5. Surirella species 



UNCLASSIFIED 



1. Bacteriastrum species 



2. Biddulphia species (ocean only) 

 :|:3. Chaetoceros species 



*4. Coscinodiscus species 



5. Navicula species 



6. Rhizosolenia species 



7. Triceratium species 



* Moderately abundant in at least some catches 



t Abundant species 



:]: Species of major importance 



In comparing the diatom species with the list published for the 1936 

 Expedition to the Gulf, we find nine species present in 1936 not listed 

 in 1937, twenty-three species present in 1937 that were not listed in 

 1936. (Table 3) 



TABLE 3 



Species Present in 1936, Absent in 1937: 



1. Achnanthes species 



2. Chaetoceros coarctatus Laud. 



3. danicus CI. 



4. Corethron criophilum Castr. 



5. Dactyliosolen species 



6. Rhizosolenia semispina Hensen 



7. styliformis Brightw. 



8. Stephanopyxis species 



9. Thalassiosira condensata CI. 



Species Present in 1937, Absent in 1936: 



1. Bacteriastrum elongatum CI. 



2. Biddulphia aurita (Lyng.) Br^b, and God. 



3. species (ocean only) 



