June 17, 1910] 



also on the flow of the water — the slower the 

 flow the more efiicient). This apparatus is 

 therefore four to seven times as efficient as the 

 ordinary air-displacement type of aerator, of 

 which Dr. Pratt, of Haverford College, was 

 so kind as to show me a working model last 

 summer. But this apparatus does not use dis- 

 placed air, since the siphon keeps the water at 

 a constant level, and there is therefore no air 

 to be displaced by water. 



Another advantage which is of great im- 

 portance is in the constancy of delivery of 

 air. A constant stream of air bubbles without 

 a second's intermission can be sent into an 

 aquarium for weeks with this aerator with no 

 attention whatever, providing the hydrant 

 works well. With the air-displacement type 

 this is of course impossible, since every time 

 the bottle is filled with water, the current of 

 air must be interrupted until the bottle is 

 emptied. 



Aside from the simplicity of the apparatus, 

 and its constancy of working, its economy in 

 the use of water will at once commend itseK 

 to all directors of laboratories who have 

 limited funds at their disposal for running 

 expenses. This aerator will deliver a con- 

 stant stream of air, using only from 50 to 100 

 cubic feet of water per month. At the rate 

 of 28 cents for 500 cubic feet of city water 

 (the rate in Kjioxville, an average rate), the 

 monthly cost of operation would be only from 

 3 to 5 cents. 



The writer's apparatus can be exactly dupli- 

 cated by referring to the following measure- 

 ments: p to a, 3 cm.; p to h, 6 cm.; p to c, 12 

 cm. ; c to d, 6 cm. ; d to e, 145 cm. ; f to g, 10 

 cm.; / to h, 32 cm.; / to Ic, 16 cm.; r to m, 

 13 cm. ;ltoo, 38 cm. ; I to m, vertical, 25 cm. ; 

 Ti, to i, 5 meters; bore of a, 1 mm.; of h, 1 

 mm.; ofc, 1.5mm. ; of cZ, 1.5 mm.; ofs, 5 mm. ; 

 of B, 5 mm. ; of C, 5 mm. ; of X>, 8 mm. ; of Tc, 

 2 mm.; depth of water in E while running, 7 

 cm.; height of E, 38 cm.; contents of E, 

 8,000 c.c. ; height of F, 24 cm. ; contents of F, 

 7.5 liters. 



Asa a. Schaeffer 



Univeesity of Tennessee, 

 March, 1910 



SCIENCE 



J 



957 



ARGYROSOMUS JOHANNA, A NEW SPECIES OF 

 CISCO FROM LAKE MICHIGAN 



Head 4.1 in length to base of caudal; depth 

 3.8; eye 6.5 in head; depth of caudal peduncle 

 3.1; snout 3.4; maxillary 2.6; mandible 2.0; 

 height of dorsal fin 1.5; distance from snout 

 to dorsal 1.9 in length ; gillrakers 10 -f 19 ; 

 longest 1.0 in eye. D. 10 A. 12; scales 9-80-8. 



Body deep, not greatly compressed, back 

 strongly arched, rising rapidly for one half 

 the distance from snout to dorsal, then more 

 gradually. Caudal peduncle high, not greatly 

 compressed. Head small, sharply wedge- 

 shaped, its height at occiput 1.9 in height of 

 body. Eye small. Lower jaw even with 

 upper; maxillary reaching nearly to center of 

 eye. Gillrakers coarse and widely set. Lat- 

 eral line straight. Scales large and thick, 

 non-deciduous. 



Color (in formalin) : lips and head pale ; 

 body dark above but not nearly to lateral line ; 

 quite pale below. Dorsally some indication of 

 stripes, longitudinally. Dorsal and caudal 

 fins with black edges, other fins pale. 



Type: No. Z12d, of the collections of the 

 Wisconsin Geological and Natural History 

 Survey, a male specimen 269 mm. in length, 

 taken in about 25 fathoms some eighteen 

 miles out from Eacine, Wisconsin. Nos. 372, 

 a, b, c and e, also Nos. 538, a, h, c and e, all 

 from the same locality, may be considered as 

 co-types. The specific name has been chosen 

 as a slight token of gratitude for my great 

 indebtedness to my life-companion. 



The table on p. 958 gives the principal 

 measurements of the specimens here included. 



Early in July, 1906, the writer made col- 

 lections of the fishes of Lake Michigan for 

 the Wisconsin Geological and Natural His- 

 tory Survey. On a trip made with Captain 

 0. Hyttel, of Eacine, to his gillnets, set some 

 eighteen or twenty miles out from that city, 

 he had a good opportunity to observe and se- 

 cure specimens of Coregonidffi. These did 

 not, however, fall easily into groups conform- 

 ing to the then known species. So the speci- 

 mens were placed into lots according to their 

 most marked external characteristics, and sent 



