THE 
VOYAGE’ OF’ H.M.8. CHALLENGER. 
ZOOLOGY. 
REPORT on the Pycnoconipa, dredged by H.M.S. Challenger during the 
years 1873-76. By Dr P. P. C. Hoek, Assistant at the Zootomical 
Laboratory of Leiden University. 
Tue beautiful and rich collection of Pycnocontpa formed during the expedition of 
the Challenger has been placed in my hands by Professor Sir Wyville Thomson, F.R.S., 
for description in the official report of the voyage.’ 
Our knowledge with regard to the Pyenogonids in general, their systematic arrange- 
ment, their geographical distribution, &c., is still very insufficient ; and with respect to 
those of the greater depths of the ocean hardly anything is known. 
The first attempt towards a monograph of the Pycnogonida is that of George 
Johnston.” His paper was published in 1837, and treats of the British species known up 
to that time. Though no special paper on Pycnogonids seems to have been published. 
previous to Johnston’s, yet there are several works of an older date, in which descrip- 
‘tions of species and genera belonging to this group occur, as well as discussions as to 
their place in the Zoological System. But as the descriptions are for the greater 
part very incomplete and the species therefore not to be recognised, these works are 
interesting only in so far as they show how much uncertainty has always been felt as to 
the place of the Pycnogonids among the Arthropoda. 
Linneus (1767) * brings the forms known to him under the genus Phalangium, 
in which also numerous land-spiders are placed, and which he ranges between 
Hydrachna and Aranea under his Insecta aptera. 
* T wish to tender my sincere thanks to Professor Sir Wyville Thomson, F.R.S., &e., who liberally trusted to me— 
though a stranger—the drawing up of this report ; at the same time to Mr John Murray who has kindly given me 
much valuable assistance. 
* George Johnston.—An Attempt to ascertain the British Pycnogonide, in The Magazine of Zoology and Botany, 
conducted by W. Jardine, P. J: Selby, and G. Johnston, vol. i., 1837. 
> Carolus Linnzus, Systema Nature, editio xii. rev., 1766. 
(ZOOL. CHALL, EXP,—PART x.—1881.) ® KI 
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