BIOGRAPHICAL SKETCH iii 
that they might have a respiratory function, but their real nature 
and significance as sense organs had passed quite unsuspected. 
Whitman showed that these sensillae are groups of tactile cells 
which differ from the scattered epidermal sense cells chiefly 
in their aggregation into groups arranged symmetrically according 
to a definite plan on one ring (now designated the neural or sen- 
sory annulus) of every somite and that they are serially homolo- 
gous with the eyes, which differ from them chiefly in the acquisi- 
tion of visual cells (Glaskérper of Leydig) and pigment cup. 
During the two years (1879-1881) which he spent in Japan 
as Professor of Zoology at the University of Tokio, Professor 
Whitman collected material fot the description of the leeches of 
that country. Under his direction most beautiful and accurate 
colored drawings were made of the species of the several families, 
but unfortunately the first part only, treating of the Hirudinidae 
or ‘“‘ten-eyed leeches,”’ was ever published. In this paper Whit- 
man’s method of analytical description, based primarily upon the 
metameric arrangement of the sensillae and the somite composi- 
tion thus made evident, was first fully applied to the family Hiru- 
dinidae. In the course of somewhat elaborate descriptions of 
the Japanese land leech (Haemadypsa japonica), the Japanese 
medicinal leech (Hirudo nipponica) and three species of Leptos- 
toma (earlier named Microstoma and now known as Whitmania) 
the somites are analysed successively and compared as respects 
their constituent elements. Comparisons are made with several 
other European, American and Asiatic genera and the previously 
unknown or only vaguely apprehended fact brought to light that 
the metameres of the different genera of ten-eyed leeches are very 
differently developed as regards the number and size of constitu- 
ent rings, particularly toward the extremities of the body. These 
observed differences in the number of rings constituting the so- 
mites are correlated with differences in the mode of life of the 
animals. In addition to their morphological value, these descrip- 
tions and the accompanying illustrations are models of beauty and 
accuracy, than which no more satisfying have been published 
before or since. 
