162 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 97 
KEY TO THE FAMILIES OF PYCNOGONIDA 
[MODIFIED FROM MARCUS, 19408, PP. 15-16; SHE FIG. 5 FOR ANATOMICAL CHARACTERS] 
1: Chelifores and spalpijpresemt. 6)" 6 ek oe i oh) ee ee 2 
Chelifores or palpi, or both, lacking or greatly reduced______--_---------- 8 
2. oheltores aud palpi both well developed: == 2.5) 2422 ee 3 
Chelifores or palpi; but not both, reduced_ 2 == 3-22" SS eee 6 
3. Palpi 17-20—jointed, first pair of legs with 12 or 13 secondary joints. 
Ammotheidae (Nymphonella) 
Palpi not more than 10-jointed; legs 8-jointed; usually with a terminal 
Clay Ro tients ed ee gered tO DR he 3 el EE ce ee ares Sa er 4 
4. Palpi 5-jointed, chelae well developed, or palpi 6-9—jointed, chelae small or 
THUD CUNY 1 GUT Ypcsctet yates ese ee res eh ee eee eee a ir 5 
Palpi 9-10—jointed; 5 or 6 pairs of legs. 
Colossendeidae (Decolopoda, Dodecolopoda) 
5. Palpi never more than 5-jointed; chelae well developed, overreaching pro- 
hoséis: 4 or-5\ pairs of legs... 2-2 2 bak Nymphonidae (p. 179) 
Palpi 6-9-jointed; chelae small, chelifores usually shorter than proboscis. 
Ammotheidae (p. 240) 
Chelifores 2-3—jointed, chelae well developed; palpi 1-4—jointed. 
Pallenidae (p. 199) 
Chelifores present, but chelae reduced to knobs, palpi 4-10—jointed__-_--__- cf 
7. Chelifores 2-3-jointed, shorter than proboscis, chelae reduced. 
Ammotheidae (p. 240) 
Chelifores 1-2-jointed, palpi never more than 7-jointed. Tanystylidae (p. 266) 
(=) 
Soe helitores or palpi lacking, but not both..l..._.--. 2-25... 2. ee 9 
Bore cheliorcs and paipr lacking. 2.7.2. 22.3.5) 6-225 Su eee ee 12 
Se Chelitores present, palpi lacking. ...2_..2...4-4....... 304 = ee 10 
Chelifores lacking, palpi present... bees) Pe eee ee 11 
iO: vOvigers 10-jointed, in both.sexes=5__ 8. - s.  = 2 Pallenidae (p. 199) 
Ovigers less than 10-jointed, in o& only_-.--_____- Phoxichilidiidae (p. 216) 
it. Palpi 4-7—jointed; small forms. 2.-.— 4.2... =--s-2-. Tanystylidae (p. 266) 
Palpi 8-10—jointed; chelifores sometimes persistent; mostly huge deep-water 
TiC a0 0 fea Se Wn. ME VR AY al ee Oe pits CO Colossendeidae (p. 268) 
12. Body slender; legs about twice as long as body; auxiliary claws present. 
Endeidae (p. 238) 
Body stout; legs short, not much longer than body; without auxiliary claws; 
A Grea pairsyOL lepea i oo. cet rete ee SS te Bk Pycnogonidae (p. 276) 
ZOOGEOGRAPHICAL DISCUSSION 
The western North Atlantic and Caribbean regions represent two 
distinct faunal provinces, the Boreal-Arctic and the American Sub- 
tropical. These two provinces overlap along the coast of the eastern 
United States between Cape Cod and Cape Hatteras. The pelagic 
fauna of the Sargasso Sea and the littoral fauna of Bermuda are ulti- 
mately related to the American Subtropical province. This is espe- 
cially true for the pycnogonids. (See figs. 6, 7.) The collections of 
pycnogonids from these regions that have been examined for this 
study include 24 genera and 70 species. All but one of the previously 
known species are represented in the collections; the missing species 
is Nymphopsis anarthra Loman, described from the Venezuela coast. 
