ON NINE BALLOON ASCENTS IN 1863 AND 1864. 193 



ventral, having a nearly equal slope at the two extremities, the anterior of 

 which is well and equally rounded, while the posterior, which is slightly the 

 wider of the two, and a little more produced below, has the dorsal curve much 

 longer than the ventral. Lucid spots consisting of a transverse row of four 

 placed close to each other, and two others at some distance in advance of these, 

 and separated from each other. Dorsal view elongated ovate. End view 

 nearly round. Hinge-margin crenulated throughout its length. Carapace 

 white, smooth, but studded with scattered opaque-white punctures. Length 

 half a line. 



Cythereis Dunelmensis, Norman (n. sp.). 



Oblong. Dorsal and ventral margins straight, but not parallel, gradually 

 inclining towards each other from the broad, well-rounded anterior extremity 

 to the rectangularly truncate posterior end. Surface of valves excavated with 

 cells, the interstices between which stand out as a network. Carapace mar- 

 gined in front by a row of bead-hke spines ; posteal extremity of ventral 

 margin bearing four large, semierect, flattened, linguiform processes ; other 

 parts of the sui'face ai-e also anned with small spines, conspicuous among 

 which is a tubercular spine at the anterior extremity of the hinge-line. 

 Length half a Hne. 



-'o'^ 



Cythereis limicola, Norman (n. sp.). 



Oblong, short ; greatest height at the commencement of the antero-dorsal 

 slope ; length to breadth as one and thi-ee -quarters to one ; subcompressed. 

 Ventral margin straight ; dorsal having a long anterior slope from the highest 

 point, and a gradual downward inclination from the same point posteriorwards. 

 Anterior extremity wide, rounded ; posterior extremity rather narrower and 

 subtruncate. Carapace having a greatly elevated longitudinal rib a little 

 within the ventral margin, from the anterior extremity of which about three 

 smaller ribs or crenations proceed divergingly to the front of the valve ; there 

 are also two nodular humps placed side by side near the posterior termination 

 of the hinge-margin. Length about one-fourth of a line. 



An Account of Meteorological and Physical Observations in Nine 

 Balloon Ascents made in the years 1863 and 1864 (in continuation of 

 thirteen made in the year 1862 and first part of 1863), under the 

 auspices of the Committee of the British Association for the Advance- 

 ment of Science, by James Glaisher, F.R.S., at the request of the 

 Committee, consisting of Colonel Sykes, the Astronomer Royal, Lord 

 Wrottesley, Sir D. Brewster, Sir J. Herschel, Dr. Lloyd, Admiral 

 FitzRoy, Dr. Lee, Dr. Robinson, Mr. Gassiot, Mr. Glaisher, Prof. 

 Tyndall, Dr. Fairbairn, and Dr. W. A. Miller. 



The Committee on Balloon Experiments was appointed last year for the 

 following purposes : — 



1st. To examine the electrical condition of the air at different heights. 



2nd. To verify the law of the decrease of temperature, and to compare the 

 constants in different states of the atmosphere. 



With respect to the first of these objects, no progress whatever has been 

 1864. Q 



