BIOLOGY, MARINE — MAYER. IO9 



harbor before this date. In 1907, however, it wih be possible to maintain 

 the laboratory open after August i, making use of the Sea Horse, after 

 the Physalia has been laid up, and thus the season may be very profitably 

 lengthened ; for very few students can arrive at Tortugas before the third 

 week in June, and the working period is too short for extended researches 

 such as the laboratory purposes to encourage. 



THE WORK OF THE LABORATORY. 



During the season of 1906 the following researches were carried out: 

 Prof. William K. Brooks and his assistant, Mr. Carl Kellner, devoted 

 much time to collecting Salpje and Appendicularia for the extensive 

 memoir upon which Professor Brooks has for some years been engaged. 

 Mr. Kellner spent four months in making surface hauls, and obtained 

 many excellent specimens of Salpa;, which he preserved in the best possi- 

 ble manner for future study. It is hoped that this collection will be of 

 material aid to Professor Brooks in the preparation of his important 

 work upon the relationships of these animals. Mr. Kellner also made a 

 special study of the structure of the house of Oikopleura. While visiting 

 the Everglades near Miami, Professor Brooks collected the eggs of Am- 

 pullaria the study of which forms the topic of his preliminary report, here 

 published. 



The Origin of the Lung in AmpuUaria, hy W. K. Brooks. 



Through the courtesy of Dr. Alfred G. Mayer I was able to visit and partially explore 

 the Everglades of Florida in March, 1906. As we pushed our way through the tall 

 reeds and grasses that cover the shallow water of the Everglades, we found great 

 numbers of small eggs, attached to the stems of the reeds and grasses, above the sur- 

 face of the water but close to it. 



The eggs were arranged in vertical rows, and were inclosed in calcareous shells, 

 resembling, in these respects, the eggs of terrestrial pulmonate gasteropods. 



We also found in the water in great abundance the prosobranchiate gasteropod 

 AmpuUaria, and when some of the older eggs were opened, they were found to contain 

 young specimens of this genus. 



The Paludinidee, which are closely related to the Ampullaridae, are aquatic, viviparous, 

 and breathe by gills ; and their structure indicates that the}' are true prosobranchs, 

 descended from and closely related to the marine prosobranchs. AmpuUaria has gills, 

 is partially aquatic, and seems to be a true prosobranch, so far as its general structure 

 is in question ; but as it has a lung, and is able to breathe air and live out of the water, 

 and as it also lays, in the air, eggs in calcareous shells, like those of the terrestrial pul- 

 monates, the question whether it is primarily a pulmonate, with secondary resemblance 

 to the prosobranchs, or primarily a prosobranch with secondary resemblance to the 

 pulmonates, suggests itself. 



As the embryonic history of the breathing organs may be expected to throw light 

 upon this question, a quantity of the eggs was collected and taken to the Marine 

 Laboratory in the Dry Tortugas. There the eggs were opened, the embryos removed 

 and sketched, and then hardened and preserved for embryological examination. 



