NATURAL SCIENCES OF PHILADELPHIA. 69 



55. Podosira maculata W. Smith. Hab. Coast of Florida, on algae. Rare. 

 Delaware river mud, also rare. Bush, river, Del., Mr. Febiger. 



56. Creswellia f e r o x . Hab. Black RockHarbor mud. Bannister's creek, 

 Rockaway mud. Wilmington marshes, Mr. Tebiger. 



Only detached frustules have heretofore been found, but these were suffi- 

 ciently characteristic to determine the species. 



57. Mastogloia a p i c u 1 a t a W. Smith. Hab. Mud from Bannister's creek, 

 Rockaway. Stonington Inlet, on algae, along with M. a n g u 1 a t a and M. 

 lanceolata. New Rochelle rocks. 



58. Mastogloia lanceolata W. Smith. Hab. Stonington Inlet, with 

 above. 



III. Species characteristic of the American coast. 



1. Eupodiscus radiatus Bailey. Hab. Rivers and aestuaries 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 algae 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. Hab. Fossil at Kaighn's Point, N. J., on 

 blue clay. Rare. Bannister's creek, Rockaway, L. I. New London harbor, 

 dredged. 



5. Auliscus cos la tu s Bailey. Hab. Mud from New London harbor. Dela- 

 ware river mud. Rare. 



A variety of A. p r u i n o. s u s , 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. 



6. Stephanodiscus N i a gar ae Ehr. Hab. Riviere du Loup, St. Lawrence 

 river, on algae. New Rochelle rocks, on algae. 



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 well 

 marked species could ever have been referred to any of the known species of 

 Cyclotella. 



7. Hyalodiscus subtilis Bailey. Hab. Atlantic coast. Very rare. San 

 Francisco. On algae from Long Beach. Abundant, and of large size. 



In this latter gathering some of the frustules attained the large size of *009 

 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 striae. In the recent and unboiled frustules the central granular disc 

 is not perceptible. H. subtilis is usually found on the axils of branching 

 algae, or adherent by a portion of its circumference to their stems. 



8. Surirella limosa Bailey. Hab. Northern Atlantic coast and rivers. 

 Common. L. I. Sound, at Rockaway, mud from creek. Delaware river. Bush 



1861.] 



