57 
MICROSCOPICAL AND NATURAL HISTORY SECTION. 
December 5th, 1881. 
Alfred Brothers, F.R.A.S., President of the Section, in 
the Chair. 
Professor A. Milnes Marshall exhibited specimens of 
the larval form of starfishes, echino'ids, holothurids, and 
crinoids, and described briefly the various stages of develop- 
ment, commenting on the great differences between the 
larval forms and the adult in each case, and also on the 
great differences between the larvae and closely allied 
groups. He considered this latter feature as indicating that 
the individual differences were acquired separately by each 
group, whilst the general resemblance in plan was due to 
inheritance, and represented the primitive ancestral forms. 
The points of individual difference were in all cases 
ultimately absorbed, and formed no part of the adult 
animal. 
The slides exhibited were prepared at the Zoological 
Station, exhibited at Naples by Dr. Dohrn. 
Mr. It. Ellis Cunliffe brought the 3rd vol. of the 
Challenger Expedition, for inspection by the members. 
Mr. J. Cosmo Melvill exhibited Limnotrochus Kirkii 
(Edgar Smith), from Lake Tanganyika, which with the 
newly allied and also recently described L. Thomsoni of the 
same author, constitutes a new genus of Mollusca. He read 
a detailed description of the genus, and pointed out its chief 
characteristics, which were the trochoid shape, deep umbilicus, 
and quadrangular aperture, likewise calling attention to the 
unusual ornamentation of the whorls, which were remark- 
