
820 THE AMERICAN NATURALIST. [Vor. XXXVI. 
from India; Zuplecta indica, var. malabarica, found on the adjacent 
Malabar coast; Xestina bombayana, agreeing “in all respects with 
those from the mainland of India"; Rhachis punctatus and Opeas 
gracilis, which are resistant forms associated with plants, with which 
they may be transported; Tornatellina manilensis; Melampus casta- 
neus, from the shore, a wide ranging species ; Leptopomoides halophilus ; 
Melania tuberculata, found from Syria to Australia and West Africa; 
and Cyrena ceylonica, of mangrove swamps. 
The pigments of corals have been investigated by Dr. MacMunn, 
who finds them “ either chlorophylloid or of a closely connected kind 
of pigment, which latter absorbs the violet end of the spectrum and 
seems generally changeable into the next kind by the agency of heat, 
etc., namely, into the dark pigment which gives the coral its dark 
color in the fresh condition.” 
The sixteen species of Chetognatha are treated by L. Doncaster. 
In his consideration of the variation and distribution of the group 
he makes many interesting points. He lays stress on the fact that 
since closely allied species are found living together without barrier 
of habitat, they can hardly have arisen through natural selection ; 
[but it must not be forgotten that there are others than spacial bar- 
riers]. Remarkable is the occurrence here of a species (Sagitta 
flaccida) previously described only by Conant from the Bahamas. 
The six dragon flies are listed by F. F. Laidlaw. One seems to be 
new, the others are well known Ceylon and Indian species, or have a 
wider distribution. 
The first installment of a series of papers on marine crustaceans 
is given by L. A. Borradaile. He here considers the Portunidz, a 
family that “is highly variable and varietal [exhibiting varieties] 
and is probably undergoing rapid evolution in many directions.” 
The account of each species is accompanied by valuable notes 
on its variation. 
The longest contribution is by Gardiner, continuing his account of 
the coral formation of the islands. It is clear and interesting. He 
assumes, first of all, the former existence of a continent connecting 
India and Madagascar, which underwent subsidence, leaving certain 
elevations where mountain peaks were. The archipelagoes occupy 
the position of one or two of these mountains. Second, the moun- 
tains became eroded by the action of oceanic currents to nearly level 
plateaux two hundred fathoms below the surface. Third, upon these 
plateaux there began to grow deep sea corals, assisted by nullipores 
and other organisms. By growing on the skeletons of their ancestors 
