On the Blood Corpuscles of the Mammiferous Animals. 1 39 



been for the curious anomaly of the heights of the stations 

 constantly coming out less on returning to them than on 

 leaving them, which the operator suspects might have hap- 

 pened from the alterations of refraction. But surely he could 

 easily have detected errors arising from such source by look- 

 ing again at the back staff after he had observed the elevation 

 on the fore staff. 



To say nothing of the absurdity of supposing that the re- 

 fraction was always decreasing during the survey, which it 

 must have been to have brought about such results, the di- 

 stances from the instrument to the staff' (44 fathoms) were 

 so small, that even supposing every day during the hours of 

 work the refraction should at first have amounted to an angle 

 equal to half the contained arc of the earth's surface, and 

 should have decreased to nothing by the time the day's work 

 was ended, and allowing a quarter of an hour to elapse be- 

 tween taking the back and fore observations, the error arising 

 from refraction would not have amounted to half an inch on 

 the whole distance from Portishead to Axmouth ; nor would 

 the daily shrinkage in the length of the staffs account for it, 

 as such difference could only affect the levels in a very much 

 less degree than the difference by the survey. It is possible 

 that there might be some very small defect in the movements 

 or the mounting of the instrument, so as in turning it round 

 from the back to the fore observation it might gain in eleva- 

 tion ; but the error appears to be so very small that it cannot 

 materially affect the results. 



Falmouth, April 30, 1840. 



XXII. Observations on the Blood Corpuscles, or Red Particles, 

 of the Mammiferous Animals. By GEORGE GULLIVER, 

 F.R.S., F.Z.S., Assistant Surgeon to the Royal Regiment of 

 Horse Guards. No. IV. 



[Continued from page 200 of the Phil. Mag. for March 1840.] 



137. A NEW species of Gibbon, (Hylobates ?) a fe- 



**- male. The most common diameters of the cor- 

 puscles l-3600th, l-3555th, l-3429th,and l-3200th of an inch. 

 Extreme sizes l-5333rd, and l-2900th. Blood from a prick 

 of the finger. 



138. White-nosed Monkey, (Cercopithecus petaurista,} a 

 male, apparently an adult. The most frequent diameters of 

 the disks 1 -3555th, 1 -3428th, and l-3200th of an inch. Ex- 

 treme sizes l-4-570th and l-3000th. Blood from a prick of 

 the tail. 



139. Marikina or Silky Tamarin, (Midas Rosalia,) an adult 



