52 Proceedings oj the Royal Society 
The author proposes to continue these experiments, at still higher 
pressures, with a modified apparatus, which will enable him to 
measure the temperature effects by means of a thermo-electric 
junction. The present process, with thermometers, is applicable 
only to liquids and to semi-liquid substances like lard. 
BUSINESS. 
Dr G. A. Gibson was balloted for, and declared duly elected a 
Fellow of the Society. 
Monday , 11th January 1881. 
Pkofessor FLEEMING JENKIN, Vice-President, 
in the Chair. 
* 
The following Communications were read : — 
1. Preliminary Report on the Tunicata of the “ Challenger ” 
Expedition. Part III. By W. A. Herdman, D.Sc., F.L.S. 
(By permission of the Lords Commissiojiers of the Treasury.) 
III. CYNTHIADiE. 
This family includes two of Savigny’s genera — Boltenia and 
Cynthia , and may be defined by their common characters if we 
omit or modify one point on which considerable stress is usually 
laid, namely, the number of lobes round the branchial and atrial 
apertures. 
The amended definition of the family is as follows : — 
Body attached, sessile or pedunculated ; apertures four-lobed, or 
having less than four lobes. 
Test coriaceous ; rarely cartilaginous or gelatinous. 
Branchial sac folded; internal longitudinal bars present, no 
papilla; ; stigmata straight (rarely absent). 
Tentacles simple or compound. 
