ZOOLOGY AND BOTANY* MICROSCOPY, ETC. 
629 
number of ancient types of Crustacea preserved in tbe great depths of 
the ocean is not a subject for wonder, if we bear in mind tbe fact that 
most of the fossil Crustacea known to us are probably littoral, or from 
the present point of view, shallow-water forms. Changes in environment 
to be met and overcome by a highly specialised littoral species in 
adapting itself to life at great depths, are presumably as great and lead 
to such structural modifications as those encountered by the littoral 
descendants of ancient species through the vicissitudes of the shore. 
As an example the author instances the family Galatheidse. In some 
instances the more primitive types of Crustacea flourish in the sub- 
littoral or intermediate depths, while the most highly specialised forms 
are more characteristic of the very shallow waters. Such is the case 
with the Paguridse. Doubtless in certain groups of lowly organised 
animals many species cast in the antique mould survive in the abyssal 
depths of the ocean, but not highly specialised forms like the stalk» 
eyed Crustacea, beings endowed with visual and respiratory organs of a 
very perfect grade. The peculiar conditions that surround the dwellers 
of the deep work great structural changes ; not only the visual organs 
become lost, but the antennae and anterior parts of the body generally 
undergo changes. The purity of the water in these still regions even 
leads to a more or less complete disappearance of the gill-scrapers. 
Thus it comes about that the Crustacea living at a great depth are apt 
to be rather specialised types further removed from the primitive 
ancestral stock than are the allied species of the shore. 
Taking the animal kingdom as .a whole, it is probable that the 
archaic forms now extant in the shallow waters of the land or coast, or 
in the moderate depths below the strictly littoral zone, far outnumber 
those surviving in the extreme depths of the sea. Heterodonta , the 
Ganoid Fishes, Limulus, Trigonia, and Lingula are all peculiar to shallow 
waters ; so are the TJnionidse of our rivers and ponds. Nautilus comes 
from very moderate depths. Pteropoda attain their maximum develop- 
ment in from 50 to 250 fathoms. The wonderful Crinoid fields lie at a 
depth of but 50 to 200 fathoms beneath the surface. 
By Prof. Agassiz’s direction coloured drawings of many of the 
Crustacea secured during the cruise were made, and some of them are 
reproduced in some of the beautiful plates which illustrate this memoir. 
It appears from a systematic tabulation of notes on colours that a 
general tendency is manifested among the Crustacea from deep water to 
assume red tints, which pass through various shades of pink, orange, 
and yellow to straw colour and ivory white. 
We have indicated but some of the many interesting points which 
are brought out in Mr. Faxon’s memoir, and we regret that our space 
does not enable us to deal more fully with this most interesting contri- 
bution to Carcinology. 
Sensory Organs of Amphibious Decapods.* — Prof. C. W. S. Auri- 
villus has an interesting article on the relations of the sensory organs 
of amphibious Decapods to their mode of life and respiration, which we 
regret we have not been able to notice before. The author discusses 
in some detail the characters of the genera Dotilla, Ocypoda , Gelasimus, 
* Nova Acta. Eeg. Soc. Scient. Upsal., xvi. (1893) Art. No. 9, 48 pp , 3 pis. 
