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THE POPULAR SCIENCE MONTHLY 



The Air-Bladder of Fishes. While en- 

 gaged in measuring a degree of the meridian 

 in 1806, the eminent physicist and astron- 

 omer Biot accidentally made the discovery 

 that fishes living at great depths have the 

 air-bladder filled with almost pure oxygen. 

 Another French scientist, Dr. Moreau, has 

 recently confirmed and extended this ob- 

 servation of Biot's. According to Moreau, 

 the air-bladder secretes pure oxygen, and 

 the presence of other gases is due to other 

 causes besides the secretion of the organ. 

 To prove this point, he examined fishes 

 which had for a considerable time lived in 

 very shallow water, and found, from several 

 analyses, that the average amount of oxy- 

 gen in the air of their swimming-bladders 

 was about sixteen per cent. He then plunged 

 the fishes in water to the depth of about 

 twenty-five feet, and found that the quan- 

 tity of gas in the air-bladder was increased. 

 The oxygen was now from forty-five to 

 fifty-two per cent. 



New Fossil Ungulates from Mexico. In 



a communication to the Philadelphia Acad- 

 emy of Natural Sciences, Prof. Cope de- 

 scribes some new fossil Ungulata found by 

 himself while employed in the Wheeler To- 

 pographical and Geological Survey of New 

 Mexico. One of these fossil ungulates, Pli- 

 auchenia Humphreysiana (a new genus and 

 species), is regarded as representing a genus 

 of Camelidoe intermediary between Procame- 

 lus occideidalts and Auchenia. P. Humphrey- 

 siana was of about the same size as the 

 former of these two animals, or somewhat 

 larger than any of the existmg llamas. 

 Another new species of this same genus is 

 Pliauchenia vulcanorum, represented in 

 Prof. Cope's collection by the left maxillary 

 bone, which proves it to have been a camel 

 of about the size of the existing dromedary, 

 and considerably larger than the preceding 

 species. The typical specimen was found 

 near Pojuaque, a village of the Pueblo In- 

 dians. Various bones of camels of the size 

 of P. vulcanorum were also found, some of 

 which doubtless belong to the same species. 

 Of Hippotherium calamarinm, a new species 

 of three-toed horse, the oral and palatine 

 parts of the skull, with the superior dental 

 series of both sides, were found near San 

 Ildefonso. Dr. Cope points out the specific 



differences between this animal and Leidy's 

 H. occidentalc, H. speciosum, and //. gratum. 

 Aphelops jemezanus, a new species of fossil 

 rhinoceros, is represented by a right man- 

 dibular ramus, found near the town of Santa 

 Clara, on the west side of the Rio Grande. 



Parental Instinct in Fishes. The Trini- 

 dad perch does not stand all alone among 

 the finny tribes in caring for the safety of 

 its young. A correspondent, after reading 

 the article "A Motherly Fish," on page 126 

 of the present volume, writes us as follows : 

 " I think it is known to our fishermen that 

 the catfish watches over its young. For 

 the fact that it does I can vouch. A friend 

 whose place of business was on the quiet 

 wharf of Havre de Grace, Maryland, had an 

 opportunity, during more than a week and 

 several times each day, of observing the 

 parental care of this fish. There were 

 always two fishes with the brood. When 

 approached, one of these would dart off, 

 while the other, naturally supposed to be 

 the mother, could be seen to flap her tail 

 against the bottom till a cloud of mud was 

 raised, concealing herself and her little ones. 

 W^hen the observer remained perfectly still 

 for some time, the water becoming clear 

 again, the mother could be seen hovering 

 over a dark mass of moving small-fry a foot 

 or more in diameter, while a little way off 

 the other fish would be in attendance." 



Monthless Fishes. Prof. Leidy lately 

 exhibited at the Philadelphia Academy of 

 Sciences an apparently mouthless fish, 

 found in the Ouachita River, Arkansas. 

 The fish is the buffalo sucker ( Catastomus 

 bubalus\ an inhabitant of the Mississippi 

 and its tributaries. The specimen is fifteen 

 inches long. The maxillaries, premaxilla- 

 ries, and mandible, are absent, and the in- 

 tegument is tightly extended between the 

 end of the snout, the suborbitals, and the 

 articular ends of the quadrates. In the 

 centre of this expansion of the skin there is 

 a small oval aperture one-fourth of an inch 

 fore and aft, and one-eighth of an inch in 

 transverse diameter. The hole is sufficient 

 to admit a current of water for the purposes 

 of respiration ; but it is difficult to under- 

 stand how the fish had procured its food. 

 The cyprinoids generally are remarkable for 



