Il8 REPORTS ON INVESTIGATIONS AND PROJECTS. 



fore we can hope to comprehend the problems of even the simplest 

 animal reactions. Professor Jennings presents the following state- 

 ment of his results : 



Preliminary Report by H. S. Jennings. 



While at the Carnegie Laboratory at the Tortugas, in June, 1905, the writer 

 devoted himself to a study of the behavior and reactions of the sea anemones. 

 The opportunities for this work were excellent, as many kinds of sea anemones 

 are found in this region, many of them large and very favorable for such 

 work. Attention was directed particularly to the problem of the modifiability 

 of behavior in these very low organisms, and most interesting results were 

 obtained along this line. A paper embodying the results of this work is to 

 appear in the November number of the Journal of Experimental Zoology. 



Prof. Henry F. Perkins pursued studies of the Medusae with a 

 view not only to discover new or interesting species, but also to 

 obtain data upon the non-radial sequence in the development of the 

 marginal otocysts of hydromedusse. His discovery of non-radiate 

 sequence in these organs is well known from his work upon Gonio- 

 nemus, and while at Tortugas he obtained abundant material for 

 extending this investigation to the Leptomedusse. He presents the 

 following summary of his work at Tortugas : 



Preliminary Report of Henry F. Perkins. 



A systematic daily study was made of Medusae taken in the tow net, and 

 thirty-four species were found. Comparison was made between the Medusae 

 oi Tortugas and those of northern stations, and studies were carried out 

 upon anatomical and other causes of habitat determination. 



■Cassiopea xamachana and C. frondosa, which were discovered in the salt- 

 water moat of Fort Jefferson, have never before been found together. 



A study of the habits and life history of Cassiopea xamachana was carried 

 out in order to draw a comparison between its behavior at Tortugas, and at 

 other localities, from which the species has been obtained. A peculiar repro- 

 duction by budding was observed in its scyphistoma larvae. 



A new hydromedusa, Cladoncma mayeri, was also found in great abundance 

 in the moat of Fort Jefferson, and its hydroid stage was found in the same 

 locality upon algae. The Medusa displays 6 oral and 9 marginal tentacles; 

 6 radial canals arise from the manubrium, but three of these immediately 

 bifurcate, so that 9 canals reach the margin of the bell. The processes of 

 production of eggs in the Medusa and of Medusa buds in the hydroid were 

 followed in detail and the habits of the animal were noted. 



A new species of campanularian hydroid, Platypyxis digitalis, was also 

 found in the moat. It is very minute, and arises singly from a stolon clinging 

 to alga. The productive calicle, with developing Medusa buds, was discovered. 



Aglanra ciliata sp. nov. is a Medusa having small tentacles and strongly 

 ciliated proboscis. It was taken on the surface in July. 



