no REPORTS ON INVESTIGATIONS AND PROJECTS. 



On my return to Baltimore, I placed the material in the hands of Mr. B. McGlone, 

 who has studied the development of the respiratory organs under my supervision, and 

 has nearly completed his work, which will soon be ready for publication. He has 

 shown that the lung of AmpuUaria is a member of the series of gill-filaments and 

 that it must be regarded as a modified gill, homologous with a ctenidium, or with more 

 than one. It is, therefore, an organ which has been secondarily acquired, and not de- 

 rived from the lung of the terrestrial pulmonates. 



Both lung and gill arise very early in the embryonic history of AmpuUaria, and at 

 about the same time. In a very young embryo, soon after the mantle makes its ap- 

 pearance, a ridge or thickening of the epithelium of the inner surface of the mantle 

 indicates the region from which the gill-filaments, the lung, and the osphradium are 

 to arise. The osphradium is developed from one end of this ridge, the gill-filaments 

 from the other, and, between the two, the ridge becomes infolded into the substance 

 of the mantle to give rise to the lung, which may be regarded as a modified and 

 invaginated gill-filament. 



The similarity between the lung of the pulmonates and that of AmpuUaria is, there- 

 fore, nothing more than a new illustration of a resemblance between organs that have 

 been acquired independently imder like physiological conditions. 



Mr. Kellner presents the following report of his work : 



The Appendicularias of the Dry Tortugas, by Carl Kellner. 



In May, 1906, I captured a number of appendicularias, and their houses, near the 

 surface of the water in the Dry Tortugas, and I am informed that similar ones were 

 found at Miami in March by Dr. Mayer and Professor Brooks. They vary in size 

 from 5 to 8 mm., and they occur in great swarms at a depth of from 5 to 8 fathoms. 

 Since returning to Baltimore, I have been studying them under the guidance of Pro- 

 fessor Brooks, with special attention to the structure of the house and the anatomy 

 and histology of the animal. My notes and drawings will be ready for publication 

 within a month. All my large specimens belong to the genus Oikopleura and are very 

 similar to, but different from Oikopleura longicaiida and Oikopleura intermedia of 

 Lohmann. 



The house is large, about 20 mm. in diameter, and nearly spherical. In its internal 

 structure it resembles the houses that have been described in other species of the genus. 



Some of the houses contained small appendicularias at various stages of develop- 

 ment, and there is no doubt that the development of this species may be studied by one 

 who is able to collect and study the young larvae and embryos from the houses of 

 living adults, but those that I have found in preserved houses are not in good condition. 



All the houses that I examined contained small elongated unicellular parasites; and 

 others, of a somewhat different shape, were found on the tails of some of my speci- 

 mens, and still others in the muscles of the tail. These three forms may prove to be 

 stages in a single life history The parasites that are found on the tail are very similar 

 to, and seem to be identical with, the bodies that are described by Lohmann as gland 

 cells. 



Dr. Leon J. Cole studied the reactions of ants and of Salpa democratica, 

 but his work is not far enough advanced for publication. 



Dr. R. P. Cowles continued his studies of the habits of the ghost crab 

 (Ocypoda arenaria) and also of the reactions of Ophiuridse. His results 

 are important and interesting and will soon be published. 



