1008 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [8] 
cells. The velum now appears as a double row of long threads, which 
surround a vaulted surface, and in the center of which lies the velar 
plate or thickening, which projects outwardly, and consists of several 
layers of cells ; from this the pharynx* (mouth) arises at a later period. 
The intestinal channel has meanwhile increased considerably both in 
length and width; the stomach has been divided by a constriction into 
a lower and upper portion, and the intestine arises from the line of junc- 
tion of thetwo. The anterior portion of the stomach develops on the up- 
per side a large round sac, the rudiment of the liver; the whole intesti- 
nal channel is coated internally with fine ciliary filaments, with the ex- 
ception probably of the hepatic protuberance. On the ventral side of 
the larva, in nearly the same place where formerly the so-called “foot” 
was located, a knob-shaped enlargement of the ectoderm begins to make 
its appearance, which is probably the rudiment of the pedal (parieto- 
splanchnic) ganglion. 
Older stages than those on which the above observations were made 
have not been examined. In order to recognize very young oysters 
which have just adhered to an object, a glazed tile covered with pure 
lime has been successfully substituted for the usual collector (stone tiles 
covered with a mixture of lime and sand); on such a collector an oyster 
measuring only 0.57 millimeter could be distinctly recognized with the 
naked eye. 
In conclusion Dr. Horst gives some information relative to a presumed 
enemy of the oyster spat. He says that in his aquarium, which con- 
tained a female (mother) oyster, which every now and then emitted large 
quantities of spat, there were also a number of actinia (Sea-anemones), 
The quantity of oyster spat decreased visibly without his being able to 
discover the cause, until one day he saw bluish-gray pellets, measuring 
but a few millimeters, come out of the mouth of an actinia. These pel- 
lets appeared to consist exclusively of empty oyster shells of the most 
diminutive size, and therefore showed that the actinia had been feeding 
on oyster spat. 
Professor Hoffmann makes the following report on his investigations: 
During the second halfof July he occupied himself with some investiga- 
tions relative to the development of the oyster. The great heat during 
July, by which the temperature in the wooden shed rose to 94°, made 
it impossible to steadily continue the observations. 
The first stages of segmentation were not observed, whilst full obser- 
vations, both on optic and actual sections, were taken during the gastrula 
stage. The gastrulat does not belong to the hollow, but rather to the 
*The Dutch word ‘‘bovenslokdarmknoop” is not found in any Dutch dictionary. Mr. 
Ryder has rendered it as the rudiment of the mouth or pharynx.—TRANSLATOR. 
t This word is not found in Webster’s English nor Dunglison’s Medical Dictionary. 
The words coelogastrula and sterrogastrula are translated hollow and solid type by Mr. 
Ryder. These are words of little consequence, except as descriptive of different con- 
ditions of development of the body cavity. All mollusca nova appear to pass at first 
through a sterrogastrula stage, followed by a coelogastrula condition.—TRANSLATOR. 
