iv INTRODUCTION. 
Survey Expeditions, so that the list of species has been more than doubled 
by the dredgings made since 1876. 
In consequence of the great delay in ^ireparing the illustrations of the 
more minute structure of the Salenidas, the Echinothurife, and many of the 
less well known Spatangoids, the concluding Part of this Report will appear 
on their completion. 
The details of the geographical distribution of the Echini of the '• Blake " 
having already been given in the Preliminary Pieports (Bull. M. C. Z., Vol. V. 
No. D, 1878, Vol. VIII. No. 2, 1880), to avoid repetitions I merely refer to 
the previously published records, as well as to the list of the dredging sta- 
tions occupied by the " Bkke " (Bull. M. C. Z., Vol. VI. No. 1, 1879, Vol. 
VIII. No. 4, 1881). These give the position, the depth, the temperature, and 
the character of tlie bottom. On the completion of the Reports by the differ- 
ent specialists, who have kindly consented to work up tlic collections of the 
" Blake," including the examination of the Ijottom samples, I hope to make 
a revision of the geographical and Ijathymetrical distribution of the various 
groups, so as to give a good picture of the animal i associated at the prin- 
cijjal localities which make up the Fauna characteristic of certain well-defined 
regions Nothing can be moi-e different, for instance, than the animals 
found associated on the rocky bottom along the southern slope (in deep 
water) of the Florida Reef, on the Pourtales Plateau, with its predominance 
of Corals, Rhizocrini, and Starfishes, from those found in the calcareous 
ooze of the trough of tlie Ciulf Stream (Lamellibranchiates, Holothurians, 
&c.) ; and again from the association of the masses of Gorgoniae, Salenite, 
and Terebratula^ off the north coast of Cuba, brought up in a single haul of 
the trawl. Nor can there be a greater contrast l)etween the inhabitants 
of the Pteropod ooze in deep water ofF the west end of Santa Cruz, witli 
its preponderance of Phormosomaa, of Asthenosoma^, and Ilyalonemae, and 
those of the forests of Pentacrini and Gorgonise, and the accompanying 
ComatuljB and Ophiurans, living in such abundance on the windward coast 
of St. Vincent. 
We may contrast, again, the deep-water Fauna off the Tortugas, in the 
coral ooze, mainly made up of a most remarkable association of Fishes 
