Powzrr.—0On Desis robsoni, 267 
“I received from Dr, E. v. Martens, of Berlin, a third species of this 
interesting genus (Desis martensii). It was collected by him on coral reefs 
at Singapore, and kindly given to me for examination. This species is 
remarkable in that it has established itself in these reefs which are only 
temporarily uncovered by the sea; Herr v. n has "e gen speci- 
mens of the spider in this locality. * * 
* * That the species discovered by Dr. E. v. Martens and Dr. Johswick,* 
can really, like our indigenous Argyroneta aquatica, Ol., live under water, 
is to me doubtful in the highest degree, for it is wanting in the outward 
visible signs of the breathing apparatus which corresponds to such sub- 
marine mode of life, and which has been anatomically demonstrated in 
Argyroneta aquatica]. It also speaks against it that yet another species of 
spider, an Atta, was found on the same coral reefs, and we may assume 
with all certainty that this is a true terrestrial form. I opine that these 
spiders, perhaps, in former times, were floated in an accidental manner 
from the land to these reefs, and now live in the holes of the coral bank, 
within which they withdraw at the time of flood, and which they close 
against the entrance of the water with a thick web. * * When once 
both sexes had been transferred to the coral reefs, Desis martensii would 
increase and form a colony there.” 
I take the liberty of quoting a further valuable communication from 
Dr. E. v. Martens on the discovery of this interesting spider, as follows :— 
“During my residence at Singapore, in October, 1861, I repeatedly 
visited a coral bank in the neighbourhood of New Harbour, of which large 
tracts were exposed above water during the ebb, at the times of new and full 
moon. My attention was chiefly directed to Crustacea and Mollusca; I tore 
off pieces of coral and broke them up to get at the ereatures hidden within. 
To my astonishment I several times observed spiders hurriedly escaping, 
the idea occurred to me at first that we ourselves had brought them from 
the shore in our clothing. I generally went with the late staff-surgeon, Dr. 
Johswiek, in a little skiff pulled by a Chinese from the frigate * Thetis ' 
which lay in the roadstead, or from the town, distant about half-a-league 
from the coral reef. This suspicion was rendered unlikely by the frequent 
repetition of the event, and conclusively disproved, as Dr. Johswick found a 
web of undoubtedly one of these spiders in an old dead mussel shell, between 
the coral, stretched sheet-like in the cavity of the shell.” { 
* Sitzungsbericht der Gesellschaft Naturforschender Freunde zu Berlin vom Mai 24, 
35. 
1864 
t ruie “ Einige Resultate aus Untersuchungen über die Anatomie der Spinnen," 
in Müller's “ Archiv. für Anat. und Physiologie," 1842, p. 300 ; und Menge “ Ueber die 
Lebensweise der Arachniden,” *' Neueste Sc Boite der xni aeta Gesellschaft,” 
in Danzig, IV. Band Hit. i, p. 23. 
1 Koch, Asi Aui: pp. 349, 350, - | 
