No. 387.] REVIEWS OF RECENT LITERATURE. 267 
three times a week. Three fission zones have been observed in one 
individual at the same time. As the animal grows in length, the 
case which it inhabits is extended, and after fission the two daughter- 
worms divide it by placing their heads together at its middle and 
forcibly breaking it; each worm then swims away with one-half of 
the old case. The fission zone is formed near the middle of some 
segment, usually back of XVII and in front of XXII. The new 
head and tail are almost completely formed before separation takes 
place. The number of somites in the new head is constant, being 
five, while twelve to sixteen segments are visible in the tail before a 
second fission begins. Worms divided by cutting regenerate the miss- 
ing part, though only enough segments are regenerated at the ante- 
rior end to complete the cephalized portion, z.e., the first five. Thus 
if two are removed but two regenerate, while if seven are taken away 
only five new segments are formed. At least three or four segments 
in addition to the five in the cephalic region are necessary for the 
regeneration of the tail. Dr. Brode gives a detailed account of the 
structure of the body wall, of the nervous system, and of the sense 
organs. Each segment is provided with four lateral nerves which 
arise from the ventral ganglion and pass to the body wall and thence 
dorsally. The epidermis is provided with a remarkable series of 
sense organs, each segment bearing two series arranged in greater 
and lesser circular bands of twelve and eight organs respectively. 
These organs are so spaced as to form twenty longitudinal rows 
extending the whole length of the body. Dr. Brode also confirms 
Hesse’s view that the so-called lateral line of oligochetes is formed 
by the accumulation of the nucleated plasma portions of the circular 
muscle fibres and cannot, therefore, be interpreted as a nervous struc- 
ture. The epidermal sense organs have no share in the formation of 
this line. The marked serial symmetry of the epidermal sense organs 
and lateral nerves is held by the author to support the colonial 
theory of the origin of metamerism. CAK 
Crustacea of Florida and the Bahamas. — Miss Mary J. Rath- 
bun is an indefatigable student of Crustacea. In fact, the mantles 
of Stimpson, Smith, Kingsley, Say, Gill, Gibbes, and all other past 
students of the group appear to have fallen on her shoulders. In 
the paper before us she describes the 127 species of brachyma, col- 
lected by the Iowa University Expedition of 1893.1 Several new 
1 Bulletin of the Laboratories of Natural History of Towa University, June, 
1898. 
