lii'isii w Aii;i; MiMusAi'. UK r.oss i.akk. i:i.i<iiau'I' 



IXKIA.NA. 



Ahslnirt. 



V. Paynk. 



Scpl<-mli(>r twenty-socond. r.M!». 1 wns inlonncd Hint medusae were ahmi- 

 (iMiil in M small avfificial laUc n<-ar KIkliaii. Indiana. Five days later I 

 visilcd llio place and vciilied the staleMicnI. In fact they were so alnuidant 

 llial (in(> could Inini; in a hundivd willi a few sweeps of the net. A second 

 visit was made two weeks later hut not a sinjile specimen could l)e found. 

 Tlie weather had hecome niuch colder, to the point of freeziui;, and no douhl 

 the change in the temperature caused their death. A few days later Mr. 

 Boss informed me that the surface of the lake was strewn with fragments 

 of medusae. All specimens examined were females. A few specimens 

 were found the previous summer. 



During the summer of 1920 the lake was watched carefully from .Time 

 twenty-first until October s(>cond. The hydroid was found June twenty- 

 eighth (m material collected June twcnty-tirst. These hydroids were ob- 

 served to form sausage shaped buds which separated from the parent and 

 formed new hydroids. Other buds remained attached, thus forming col- 

 onies. The largest colony found hail seven hydroids. A third type of bud 

 formed the medusa. 



The first medusa in the siuunicr of 1920 was taken July sixteenth. It 

 was about one-half inch in diameter. The rest of the summer they were 

 alMuidant, but not po numerous as they were on my first visit of the previ- 

 ous year. Again all the medu ae wer(> females. This, along with the fact 

 that on previous discoveries of this medusa all the specimens were males, 

 has puzzled me somewhat. The females became sexually mature and shed 

 their eggs but they did not develop so far as my ob'-ervations went. IMank- 

 ton catches at all seasons and depths have shown no free swimming larvae. 

 Xeither has a close examination of the weeds, sticks, stones, and surfaces 

 of boards and posts shown anything of the sort. Kut why is there only one 

 sex? I do not know- but the facts lead me to wonder whether the hydroids 

 may not be male and female producing. 



How the forms got into the lake is doulitful. The hydroids are very small 

 and might occasionally become attachcil to fishes and thus be transferred. 

 Xeither do I see any reason why they might not be carrie<l by wading birds. 



The hydroids live ovi'i- the winter in the form of contracted masses. 



