Biological Studies on Corymorpha. 397 



The hydranth has a single whorl of eighteen to thirty proximal 

 tentacles with a spread of more than twenty-five millimeters. 

 The proboscis, terminating in the mouth, is crowned with forty to 

 sixty distal tentacles. Just within the proximal tentacles are 

 several peduncles which bear numerous medusoid gonophores. 



The stem is anchored by a tangle of filaments which arise on 

 the longitudinal canals, beneath the perisarc, usually in pairs. ^ 



II. habitat; food. 



Corymorpha palma is a semi-tropical species, dwelling farther 

 to the south than any of the other North American species of the 

 genus. It has been found as yet only in two localities: in San 

 Diego and San Pedro harbors, both on the southern coast of 

 California. It lives under similar conditions in both places. At 

 San Diego it was found in a slough near the mouth of the harbor, 

 on a muddy bottom which was exposed at mean low water. At 

 San Pedro it has flourished at various points in the harbor, always, 

 however, on muddy flats. It occurs usually in definitely circum- 

 scribed patches, which change their position apparently with 

 much caprice from year to year. A favorite location is along some 

 small stream that drains the mud flats as the tide ebbs. 



Copepods are numerous on the mud, which often carries 

 patches of green composed of diatoms and other chlorophyl- 

 bearing protista. All of these organisms seem to serve as food for 

 Corymorpha, though the copepods form the staple article of diet. 



III. activities of the polyp. 



Corymorpha captures crawling diatoms and copepods by bend- 

 ing its column in a half circle and sweeping the sand with its 

 tentacles. Floating organisms are caught when the column is in 

 its usual erect position, with proximal tentacles fully extended. 

 The oral tentacles are almost always active, bending restlessly 

 now outward, now inward, now moving simultaneously, now 

 independently. The proboscis is extremely mobile, capable of 

 lengthening into a narrow stalk or contracting into a sphere, or 



'For a diagnosis of tlie species, see my paper just referred to. 



