11 
_ 55. Podosira maculata W. Sm'th.—Hab. Coast of Florida, on alge. Rare. 
a Delaware river mud, also rare. Bush river, Del., Mr. Febiger. 
56. Greswellia ferox.—Hab. Black Rock Harbor mud. Bannister’s creek, 
ear ay mud. Wilmington marshes, Mr. Febiger. 
- Only cetached frustules have heretofore been found, but these were suffi- 
ciently characteristic to determine the species. 
nett 57. Mastogloia apiculata W. Smith.—Hab. Mud from Bannister’s creek, 
Piticsway. Stonington Inlet, on alge, along with M.angulata and M. 
lanceolata. New Rochelle rocks. 
_—s«#wBS. Mastogloia lanceolata W. Smith.—Hab. Stonington Inlet, with 
_ above. 
If. Species characteristic of the American coast. 
1. Eupodiscus radiat us Bailey.—Hab. Rivers and estuaries from Charles- 
ton to Key West. Savannah rice field mud. Common. St. Mary’s river 
mud, and at Fernandina, Florida. Common in tidal mud; also in alge from 
pier at St. Augustine’s. 
2. Auliscus pruinosus Bailey.—Hab. Long Island, at Black Rock. 
3. Auliscus punctatus Bailey.—Hab. Rice field mud, Savannah river. 
Rare. 
4. Auliscus radiatus Bailey.—Hub. Fossil at Kaighn’s Point, N. J., on 
_.  blueclay. Rare. Bannister’s creek, Rockaway, L.I. New London harbor, 
dredged. 
5. Auliscus ce latus Bailey.—Hab. Mud from New London harbor. Dela- 
ware river mud. Rare. 
A variety of A. pruinosus, having three processes, occurs in Savannah 
river mud. All these species vary much in their markings, and occasionally 
so nearly approach each other in general character, as to make it very doubt- 
ful whether they ought to be kept apart. 
a 6. Stephanodiscus Niagar« Khr.—Hab. Riviere du Loup, St. Lawrence 
3 river, on alge. New Rochelle rocks, on alge. 
This fresh water species is quite common in our northern lakes and rivers, 
_ but as a marine form is rarely met with. It attains a large size in Lake Mem- 
phremagog, Canada, and in one locality, Skinner’s Island, a remarkably fine 
variety occurs. When marine or brackish in its habitat it undergoes a marked 
diminution in size, preserving, however, the characteristic spines and other 
specific distinctions. In Kiitzing’s description, (Species algarum, )it is spoken 
of as having a non-radiate granular centre, but in all the specimens which 
have fallen under my notice, this character has been wanting, and the centre 
both radiate and granular. It is difficult to understand how this very we!! 
marked species could ever have been referred to any of the known species of 
Cyclotella. 
7. Hyalodiscus subtilis Bailey.—Hab. Atlantic coast. Very rare. Sam 
Francisco. On alge from Long Beach. Abundant, and of large size. 
In this latter gathering some of the frustules attained the large size of ‘(0% 
in diameter. The F. V. is very narrow and linear, and the endochrome of a 
deep grass green color, dries in bands usually affecting the curvilinear course 
of the striz. In the recent and unboiled frustules the central granular disc 
is not perceptible. H. subtilis is usually found on the axils of branching 
alge, or adherent by a portion of its circumference to their stems. 
8. Surirella limosa Bailey.—Hab. Northern Atlantic coast and rivers. 
Common. L. IJ. Sound, at Rockaway, mud from creek. Delaware river. Bush: 
