ATLANTIC AND CARIBBEAN PYCNOGONIDA—HEDGPETH 159 
Stanley C. Ball, of the Peabody Museum, for the loan of the large 
collections from that museum, which include many valuable speci- 
mens listed in the literature, and Dr. Fenner A. Chace, Jr., formerly 
of the Museum of Comparative Zoology, for the loan of material and 
the time he took in my behalf while at Cambridge. The greater part 
of this study was carried out during the author’s residence in Cali- 
fornia, 3,000 miles from the eastern museums, and required con- 
siderable correspondence and shipment of collections back and forth 
across the continent. This was an imposition on the time and patience 
of those who were kind enough to help me, and their generous coopera- 
tion has had no small part in making this report possible. Also I wish 
to thank John C. Armstrong, assistant curator of invertebrates in the 
American Museum of Natural History, for the loan of the pycnogonids 
in the collections of that museum. I am particularly indebted to 
Dr. Louis W. Hutchins for permission to make use of the collections 
made by the Woods Hole Oceanographic Institution fouling survey 
in advance of the comprehensive report on that collection in order 
that all the species found in the area of this report might be included 
in it. 
CLASSIFICATION 
The Pycnogonida constitute an independent class of the Arthropoda, 
with characters indicating affinities with both the Arachnida and 
Crustacea.’ Their systematic position has been well summarized 
by Marcus (1940b, p. 129): ‘‘The Pantopoda do not in any phase 
possess the crustacean biramous limbs nor the arachnomorphous 
body composed of cephalothorax (prosoma) with six pairs of append- 
ages and abdomen (opisthosoma). Therefore it seems advisable to 
consider them as a separate class of the Arthropoda—or the Euar- 
thropoda, if the Malacopoda (Onychophora and Tardigrada) are 
left aside—and not to include them in the Crustacea or Arachno- 
morpha (Merostomata and Arachnoidea) and thereby make diagnoses 
for these classes impossible.’’ 
There are about 50 genera and 500 species of pycnogonids, but the 
group is so compact that many of the families are merely categories 
of convenience. Although attempts to divide the Pycnogonida into 
orders have been unsuccessful, there are two general groups. The 
first group, including the families Nymphonidae, Ammotheidae, 
5 Aside from considerations of personal sentiment and of priority (Pycnogonides Latreille, 1810; Podo- 
somata Leach, 1815; Pantopoda Gerstaecker, 1863), the majority usage of Pycnogonida by English, 
Scandinavian, French, and American writers overrules the Pantopoda of the German, Russian, and other 
writers. Norman (1908) resurrected Leach’s Podosomata because he did not believe that the name of a 
class should be derived from that of a genus included init. Why not? (Cf. Bouvier’s (1923, p. 3) passionate 
comments on the subject.) 
In the recent revision of A. S. Pearse’s ‘“‘Zoological Names’’ (Duke Univ. Press, 1947) it would appear 
that I have sanctioned, the retention of orders, since I am cited as the authority for the pycnogonid names 
in this brochure. I suspect the author was reluctant to adopt such a radical excision from his list. 
