210 



THE AMEEICAN MONTHLY 



[November, 



melting some fresh ice from the same 

 locality living specimens w^ere fovind. 

 This ice was full of air bubbles and 

 vs^ater drops. Professor Leidy recog- 

 nized the annelid as new, and applied 

 to it the name Luvibricus glacial is. 

 It was 4-6 lines long and 0.15 to 

 .25 mm. thick. The ice in which 

 the annelids occurred vs^as full of air 

 bubbles. In clear ice none were 

 found. This suggests the caution 

 that, in selecting ice for using, spongy 

 ice from a stagnant pond should be 

 avoided. 



A New Form of Fresh- Water 

 Coeleiiterate. 



BY DR. M. USSOW.* 



Owsjannikow and, later, Grimm 

 have mentioned a parasite upon the 

 egg of the sterlet {Accipenser riith- 

 efttis) of the river Volga. This para- 

 site proves, upon investigation, to be 

 a coelenterate like the fresh-water ge- 

 nus Hydra^iixwd forms a new genus and 

 species called by Dr. Ussow Polypo- 

 diuni hydriforme. Its life cycle in- 

 cludes three phases, viz : I. Parasite 

 in the egg of host, in the form of a 

 cylindrical spirally-wound pouch 

 with numerous buds upon it. 3. Free 

 living stage derived from No. i by 

 budding from stolon upon it ; it has 

 34 or 13 or 6 tentacles. 3. The ma- 

 ture sexual stage not differing much 

 externally from 3. 



o 



Tree-Climbing Cray-Fish. 



To show how a flood or over- 

 supply of water will at certain times 

 alarm these little creatures, a gentle- 

 man residing in Freeport, Illinois, 

 informed me that not many months 

 ago they had some very heavy rains 

 that greatly increased the volume of 

 the little river running through the 

 town. The water gradually rose un- 

 til numbers of quite large trees were 

 submerged, and the stream was almost 

 twice its ordinary width. Such an 

 unusual occurrence naturally attracted 



♦From Morphol., Jahr. b. 12, p 137. 



considerable attention, and my in- 

 formant and a number of others vis- 

 ited the trees several times, and w^hen 

 the river was at the highest they pre- 

 sented a strange appearance from a 

 little distance. Their trunks seemed 

 to have changed color from the water 

 up to the branches, and on closer in- 

 spection it was found that they were 

 completely encased with cray-fish, 

 which covered every available space, 

 crowding upward by hundreds, 

 clinging to the bark and to each 

 other, in some spots packed one upon 

 another four and five deep ; every mo- 

 ment added to the throng, new ones 

 eiuerging from the water, while those 

 above, urged on, crept out upon the 

 branches, and completely covered 

 them, presenting a novel and interest- 

 ing sight. The animals in many 

 cases retained their positions for sev- 

 eral davs, and did not seem to be af- 

 fected by their stay out of water. 

 The occasion, however, was taken 

 advantage of by the people, who 

 came with buckets and brooms arid 

 swept them from the trees by hun- 

 dreds, storing them up for future use. 

 The cray-fish in certain portions of 

 the Western country is a pest to the 

 agriculturist, and the work of these 

 little creatures often greatly increases 

 the labor and expense of breaking 

 up land, especiallv after the burrows 

 or mounds have stood for many years, 

 the vegetation that has grown upon 

 them often increasing their size to 

 mammoth proportions . — From 

 ' Some Peculiar Habits of the Cray- 

 Fish^^ by C. F. Holder, in Popu- 

 lar Science Monthly for October. 

 o 



— The November number of the Popti- 

 lar Scieticc Monthly contains a most inter- 

 esting article upon Chevreul, the veteran 

 French chemist, who has recently cele- 

 brated his one hundredth birthday. In 

 1806 he pubhshed his first important sci- 

 entific work. At 1825 he was mentioned 

 in the Lancet as one of the ablest of 

 French chemists. He is a proof of the 

 proposition that study in itself is not very 

 killing, and that regular habits and diet 

 are commendable. 



