12 



TWO NE"W SPECIES OF THE GENUS PEEIDINIUM. 



of the species noticed by myself in sediment collected from the Croton water by 

 means of a filter at the Astor House, in New York city : — 



Amphiprora alata, Ehr. 

 Amphora oyalis, Ehr. 

 Cocconema cymbiforme, Ehr. 



" , gibbum, Ehr. 

 Eunotia arophioxys, Ehr. 



" gibba, Ehr. 

 Gallionella crotonensis, B. 



" aurichalcea, Ehr. 



Gomphonema acuminatum, Ehr. 



" constrictum, Ehr. 



DiATOMACEAE. 



Navicula affinis, Ehr. 

 " cuspidata, Ehr. 

 " inaequalis, Ehr. 

 " mesolepta, Ehr. 

 " (Gyrosigma) hippocampus, 



Hass. 

 " (Gyrosigma) Spencerii, B. 

 " (Pinnularia) dicephala, Ehr. 

 " (Pinnularia) elliptica, Ehr. 

 " (Pinnularia) peregrina. 



Stauroneis gracilis, Ehr. 

 Stephanodiscus Niagarae, Ehr. 

 Surirella solea, Ehr. 

 Synedra acus, Ehr. 



" capitata, Ehr. 



" ulna, Ehr. 



" valens, Ehr. 



" vitrea. Kg. 

 Tabellaria flocculosa, Ehr. 



" fenestralis, Ehr. 



Ankistrodesmus falcatus. 

 Closterium lunula. 

 Monaotinus octonarius, B. 



" duodenarius, B. 



Pediastrum ellipticum. 



" heptactis. 



Cyclops, several species. 

 Lynceus, several species. 



Desmidieae. 

 Pediastrum Napoleonis. 



" pertusum. 



" simplex. 



" tetras. 



Scenedesmus obliquus. 



Infusoria and Crustacea. 

 Cypris, several species. 

 Spicules of spongilla. 



Scenedesmus obtusns. 



" quadricaudatus. 



Staurastrum dejectum. 



" enorme. 



" gracile. 



Anguillulae, &c. 



viir; 



Two New Species of the Genus Peeidinium. 

 1. Peridinium long^ipes, B. 



(Plate, Fig. 35.) 



Body triangular, rough ; angles produced into very long ciliated processes, of 

 which the two frontal ones are longest. Body crossed obliquely by a ciliated 

 groove. Habitat, St. George's Bank. 



This species is distinguished from P. tripos, of Ehrenberg, by its roughly granu- 

 lated surface, its ciliated processes, and its triangular, not urceolate body. 



Many specimens of this fine species were found in the stomach of the Botryo- 

 dactylis grandis, Ayres, from St. George's Bank. 



3. Peridininm depresisunij B. 



(Plate, Figs. 33, 34.) 



Lorica obliquely depressed, with one large conical posterior process, and two 

 smaller conical frontal processes; the latter separated by a deep notch. Surface 

 granular and reticulated. 



Habitat with the preceding. 



Both of these species of Peridinium were doubtless furnished with a proboscis 

 when living, and, like the other marine species of this genus, were probably phos- 

 phorescent. 



