1924] Lewis,—The Flora of Penikese 
as shown by a careful study of the girdle 
view. Also Cleve’s figures show a strong 
central dilation not present in this species. 
He also implies that the costae are striate 
which is certainly not the case here. 
The identifications of the Penikesediatom 
species were verified by Dr. Albert Mann, 
Diatomist of the Carnegie Institution of 
Washington. Following is a list of the 
species, separate for each pond or sample, and a complete list of all 
the species from the island. 
Fig. 1. 
P. G. sp; n, > 1000 
Navicula nanella 
PENIKESE IsLAND HARBOR—PLANKTON DIATOMS. 
Achnanthes longipes Ag. 
Actinocyclus Ehrenbergii Ralfs 
Actinoptychus undulatus E. 
Chaetoceros coarctatum Laud. 
Chaetoceros decipiens Cl. 
Chaetoceros didymum E. 
Chaetoceros (Bacteriastrum) varians 
Laud. forma furcata Grun.; Disc. 
0.028 mm. diam. 
Cocconeis scutellum E. 
Coscinodiscus excentricus E. 
Fragillaria hyalina K. 
Grammatophora marina K. 
Liemophora flabellata Ag. 
Liemophora Lyngbyei K. 
Licmophora tincta (Ag.) Grun. 
Mastogloia exigua Lewis 
Melosira Borreri Grev. 
Melosira sulcata K. 
Nitzschia closterium (E.) W. 8. 
Nitzschia longissima (Bréb.) Ralfs 
Nitzschia Sigma W. 8. 
Pleurosigma elongatum W. S. 
Rhabdonema Adriaticum K. 
Rhizosolenia hebetata var. semispina 
(Hensen) Gran. 
Rhizosolenia setigera Brightw. 
Striatella unipunctata Ag. 
Synedra Hennedeyana Greg. 
Tropidoneis Lepidoptera (Greg.) Cl. 
PENIKESE ISLAND HarBor—Bottrom DIATOMS. 
Dredging-depth 2 feet, near shore. 
Achnanthes longipes Ag. 
Actinocyclus crassus W. 8. 
Actinoptychus undulatus E. 
Amphora Grevilleana Greg. 
Amphora obtusa Greg. 
Auliseus caelatus var. strigillata A. S. 
Biddulphia Favus (E.) V. H. 
Campylodiscus Thuretii Bréb. 
Cocconeis scutellum E. 
Coscinodiseus excentricus E. 
Coscinodiseus Oculus-Iridis var. Mor- 
siana Grun. 
Eupodiscus Argus E. ( 2 Aulacodiscus 
Argus (E.) A. S3: 
Grammatophora macilenta W. 8. 
Grammatophora marina Grun. 
Grammatophora serpentina E. 
Hantzschia marina (Donk.) Grun. 
Hyalodiscus stelliger Bail. 
Melosira sulcata K. 
Navicula aspera E. 
Navicula Bombus E. 
Navicula clavata var. caribaea Cl. 
Navicula didyma K. & E. 
Navicula distans (W. S.) Cl. 
Navicula exempta W. 8. 
Navicula forcipata var. densistriata 
A. 8. 
