ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
477 
individuals of a single species sometimes differ more from each other, as 
regards their metamorphosis, than the individuals of two very distinct 
species.” In the full memoir shortly to b ) published this phenomenon 
is carefully described in A. heterochelis and A. Saulcyi ; in the case of the 
first of these the difference seems to be geographical, while in that of 
the second it is in direct relation to the conditions of life. The species 
live in the tubes and chambers of two species of Sponges, and the 
metamorphosis of those that live in one is quite different from that of 
those in the other. As Prof. Brooks remarks, this phenomenon is highly 
remarkable, and worthy the most thorough examination, for it is a 
surprising departure from one of the established laws of embryology — 
the law that the embryonic and larval stages of animals best exhibit 
their fundamental affinities and general resemblances, while their specific 
characteristics and individual peculiarities make their appearance later. 
It must, however, be borne in mind that the early stages of two closely 
related species may differ greatly ; one may lead a free life, while the 
other is protected by the parent. Among Echinoderms we find marked 
differences between the complicated metamorphosis of the free larvae and 
the history of those which are developed in brood-pouches. These con- 
siderations do not apply to the case of the two forms of the same species, 
as here described. 
Considerable variations obtain in the habits and coloration of 
Alpheus ; one species is found in green and in brown sponges, and it is 
suggested that the parasites of the green sponge were born in the brown 
variety, and after attaining considerable size, migrated to the green 
sponges, when they adapted themselves to their slightly different sur- 
roundings, growing to three or four times their former size, and the 
females acquiring bright green eggs, which become a source of protection 
in their new habitat. 
From a study of the embryology of Alpheus , Mr. Herrick is brought 
to the conclusion that the germinal layers in the early stages of develop- 
ment have not the significance* that is usually assigned to them. 
Development in general is characterized by great secondary modifications, 
and there is considerable retardation in the differentiation of the layers, 
and especially of the endoderm. 
The Stomatopoda do not carry their eggs about with them, but 
deposit them in their deep and inaccessible burrows under the water, 
where they are aerated by the currents of water produced by the abdomi- 
nal feet of their parents. Larval life is long, and thus the larvae undergo 
secondary modifications, which have no reference to the life of the 
adult. 
Decapod Crustacea of Kingston Harbour, Jamaica.*— Mr. J. E. 
Benedict gives a list of the thirty-eight Decapods collected in Kingston 
Harbour; among them is the representative of a new genus called 
Areograpsus (A. jamaicensis sp. n.) and of two new species — Eucratoplax 
spinidentata and Sesarma hidentata. 
Larval Forms and Relationships of Cancridse.f — Dr. G. Cano has 
studied the post-embryonic development of Cancridae with the view of 
* John Hopkins Univ. Circ., xi. (1892) p. 77. 
f Bull. Soc. Entomol. Ital., xxiii. (1891) pp. 146-58 (2 pis.). 
