BIOLOGY OF THE OYSTER-GROUNDS OF SOUTH CAROLINA. 
347 
ANIMAL ELEMENT OF OYSTER FOOD. 
(a) Crustaceans are uncommon, even the more minute entomostracans. Fragments 
of a copepod were twice noted, but were of so large a size (antennae, meral plates, and 
leg segments), that they were probably ingested piecemeal, together with unwelcome 
mud and sand. This view is apparently confirmed by the presence in the same 
stomach of such out-of-the-way articles of diet as the antennae of the sand fly ( Chi- 
ronomus) and bunches of cells of pine and palmetto. Eggs of shrimp-like forms have 
occasionally been noted. 
(b) Vermes. Eggs of annelids have been found, but nothing rotifer-like. 
(c) Protozoans constitute the main animal element of oyster food. In some locali- 
ties, where there occurs a direct ingress of the ocean waters, numbers of Foraminifera 
are occasionally found, Polystomella , Textilaria, and liotalia being the prominent types. 
But many of these were probably stirred up by some unusual action of the water. 
Oysters from a well-examined locality, after a heavy rain, showed a large proportion 
of Foraminifera , many dead shells among them. The monothalamian rhizopods, 
Arcella. and Fuglypha, are abundant in several localities. Infusorians are uncommon. 
But few bell animalcules were found throughout the season, even in the stomachs of 
those oysters that harbored Pinnotheres. A number of the ciliates were noted, espe- 
cially Trachelius. In almost every specimen would be found, separate, however, num- 
bers of a small gregarine, a monocyst, perhaps in a young stage. Parasitic Opalina is 
also not uncommon. 
Spicules may finally be mentioned as among the valueless animal relics found in 
the oyster stomach. These in a cleaned condition are given off in myriads by the 
disintegration of sponges, mainly Cliona , and of gorgonian corals, and have been 
ingested while in process of settling. 
PLANT ELEMENT OF OYSTER FOOD. 
(a) Diatoms. — The diatoms taken from the oyster offer a rich field for the student 
in rare forms and variety of species. Many of the diatoms named in the New York 
report as the food of the Long Island oyster have been found to occur in the Carolinian 
oyster. In the southern oyster the greater saltness of the water is at once apparent 
in the richness of many forms of food regarded as exclusively marine, as Triceratium 
favus and several Triceratia, apparently undescribed, that I have seen from the Carib- 
bean Sea. The lack of brackish- water diatoms affords a marked contrast to the Long 
Island forms. In the present connection it would hardly be of value to give the list 
of even those which I have been able to identify. The diatoms of the Carolina waters 
have never been thoroughly studied systematically, and there are very many, especially 
of Cymbella , Favicula , and Nitzschia , that are probably undescribed. 
The bulk of the diatoms consisted of minute species of elongated forms. The 
prominent genera represented were Navicula ( didyma E., a very common species), 
Amphora , Cymbella , Pleurosigma ( littorale W. Sm., a prominent species), Synedra , 
Qrammatophora , Surirella ( limosa Bai. and gemma E., prominent), and a number of 
species of Amphipleura. Of the rounded forms, three species were common in every 
locality examined, Cyclotella rotula , Coseinodiscus radiatus , and Actinocyclus undulatus. 
The following genera occur prominently but sparingly throughout the State: Tricera- 
tium, Biddulphia , Stepha nopyxis, and Cerataulus. 
