386 NATURAL SCIENCE. May, 
tissues chiefly affected ; of complex anomalies, like hermaphroditism, 
apparent or real; and of monsters single or double. The illustrations 
are very useful, and as appropriately horrible as the subject demands. 
There is an index ; full table of contents ; and glossary of terms. 
Altogether it is a most useful book, and is to be commended to 
all anatomists and embryologists. P.-C 
THE EMBRYOLOGY AND METAMORPHOSIS OF THE Macroura. By W. K. Brooks, 
Professor of Animal Morphology in the Johns Hopkins University, and F. H. 
Herrick, Professor of Biology in Adelbert College. National Academy of 
Sciences, vol. v., Fourth Memoir. Pp. 325-576, with 57 Plates. 
In this beautiful memoir the authors have made a notable contribu- 
tion to knowledge of the development of the Macroura. Animals 
which, like the Crustacea, pass through a series of successive moults 
during their larval life, naturally exhibit a series of gradations leading 
towards the adult condition, Fritz Miiller and Claus showed that 
in this group a very large number of orders, families, genera, and 
species display the relation between ontogeny and phylogeny. At 
the same time, Claus pointed out that an equally large number of 
adaptive larve are to be found, and in the introduction to this 
memoir Dr. Brooks strongly insists on the necessity of careful and 
exhaustive study in each case before the significance of a larval 
history can be understood. The survival of larve living free in water 
depends on their adaptation to their present environment, and so 
recapitulation of ancestral stages in the present metamorphosis must 
depend to a large extent on the persistency of those external condi- 
tions to which the larve were originally adapted. 
The chief forms studied in this memoir are Stenopus hispidus, 
Alpheus, and Gonodactylus chivagyva. In addition to anatomical and 
embryological detail, a number of side issues of genera] interest turn up. 
Thus one would expect (says Dr. Brooks) that the least specialised 
species are the most widely diffused. But the larvee of Stenopus 
hispidus, although Stenopus is one of the most highly specialised of the 
Crustacea, are most widely distributed. Specimens from the Indian 
Ocean and the South Pacific agree with those from the West Indies 
down to the most minute marking. ‘It is well protected from 
enemies by a thorny armour of hooked spines which cover all the 
upper surface of its body and limbs, and, as all the hooks point 
forward, the attempt of an enemy to swallow a Stenopus must be 
difficult and painful.” 
Many of the species of Alpheus live as parasites in the canal of 
sponges, and individuals of the same species living in different species 
of sponges may differ greatly in colour and habits. 
In Alpheus and in Stenopus, after impregnation takes place, the 
nucleus divides and a syncytium of eight nuclei is found. In Alpheus 
there is a slight invagination and a modified gastrula is found. But 
in all the accounts of development given readers will be struck by the 
want of distinctness in the separation and formation of the germinal 
layers. It certainly seems as if the familiar successive origins of the 
germinal layers are present only in a very vague manner in this 
group. 
The account of the larve of Gomodactylus chivagra is specially 
valuable, as so little is known of the Stomatopoda. In the present 
work, Dr. Brooks is able to confirm most of the results he reached 
in the ‘‘ Challenger ” monograph. 
