M i CK os co PIC A i, OBSERVATIONS'. 41 



I first detected this species in 1848, in soundings from Mobile Bay, and subse- 

 quently I have found it at Savannah, Ga , and St. Augustine, Florida. It is a 

 curious and interesting form, with the shape of a Zygoceros, and the spines of a 

 Denticella. 



INFUSORIA. 



1. DIFFLUGIA SPIRALIS, B. Lorica subglobose, minutely granulated; upper 

 surface with a spiral suture of two or three turns Pseudopodia long, numerous, 

 constantly changing position. 



Very common throughout the United States. M. Le Clerc mentions spiral 

 corrugations as occurring on the D. Proteiformis, Ehr. His remark, doubtless, 

 alludes to the D. spiralis, which, I think, should be distinguished from the other 

 form. 



2. MELICERTA NUDA, B. PI. 3, figs. 8, 10. This is, possibly, only a condition of 

 M. ringens ; but no allusion is made, in the works to which I have access, to 

 any state of that species in which the granules are not present upon the case. 

 Numerous specimens were seen at Enterprise which were evidently full grown, 

 and which contained eggs, and yet the case was perfectly free from granulations, 

 being clear and transparent as glass. I have referred to such specimens by the 

 name of M. nuda. 



3. PERIDINIUM CAROLINIANUM, B. PL 3, figs. 4, 5. Large, processes three ; two 

 on one side, and one on the other of the middle groove. Proboscis in the sinus 

 between two processes. Surface coarsely granulate. Color, yellowish brown. 



The proboscis moves very rapidly, sometimes in irregular undulations, and 

 sometimes revolving so rapidly as to produce the appearance of a cone, as 

 represented in the fig. of Peridinium fusus, Ehr., given in Pritchard's Infusoria. 

 PI. 4, figs. 2, 23. An appearance of an orifice is obscurely seen on the under 

 side, near the insertion of the proboscis. When mounted in Canada balsam, 

 the shell becomes nearly invisible. The motions of the living animal are very 

 active. I could detect no trace of phosphorescence on agitating in the dark a 

 phial which contained myriads of the living animals. 



This fine species occurs in vast quantities among the roots of Lemna in the 

 " Back-waters" of rice fields, Grahamville, S. C. I also found it near Savannah 

 and in the lakes of Florida, at Enterprise, Pilatka, &c. 



4. ROTIFER VESTITUS, B. PI. 3, figs. 9 and 14. Body large, elliptical, com- 

 pletely covered by a transparent, jelly-like case, which does not become wrinkled 

 during the motions of the animal. 



Hab. Enterprise, Fa. 

 6 



