BULLETIN OF THE NATURAL HISTORY SOCIETY. 
235 
RHABDONEMA. 
Rhabdonema. Frustules united in elongated filaments, attached or stipitate, 
annulate. Annulae plane, cellulate on their circumference, forming 
internal septa. Valves elliptical, striate, with a median line. Striae 
bead-like, and giving a latticed appearance. (Plate II, Fig. 14.) 
A. arcuatum Lyn. Common in Passamaquoddy region. 
RAPHONEIS. 
Raphoneis (Doryphora). Frustules free, simple or shortly stipitate. Front 
view narrowly linear. Valves much broader, with transverse dotted 
striae and a median longitudinal line. 
R. amphiceros Ehr. Kennebecasis. Common. 
R. (Doryphora) Boeckii. Kennebecasis, Passamaquoddy. (Plate II, Fig. 15.) 
RHIPIDOPHORA. 
Rhipidophora. Frustules stipitate, on front view cuneate, in lateral view 
obovate lanceolate, Inflected at larger extremity and traversed by a 
median line. (Plate II, Fig. 16.) 
R. sp? Bocabec. Passamaquoddy, Miramichi. 
RHIZOSOLENIA. 
Rhizosolenia (Filamentous). Frustules sub-cylindrical, greatly elongated, 
silicious, annulate. Annulae broadly cuneate. Surface striated, extremi- 
ties calyptriform, pointed with a bristle. 
R. setigera? Passamaquoddy Bay, in plankton gatherings. (Plate II, 
Fig. 18.) 
R. ? Several forms not determined. (Plate II, Figs. 17-19.) 
SKELETONEMA. 
Skeletonema. This is a very rare genus of Diatoms not described in many 
standard works. Frustules cylindrical and resembling Melosira, like 
the latter united in chains of many individuals, but with considerable 
intervening spaces crossed by groups of fine hair-like processes. The 
form represented in Plate was obtained from plankton gatherings in 
Chamcook Harbor. 
Sk. Sp undetermined. (Plate II, Fig. 20.) 
