ATLANTIC AND CARIBBEAN PYCNOGONIDA—HEDGPETH i61 
The relationships and comparative importance of the families 
have been discussed at greater length elsewhere (Hedgpeth, 1947). 
As can be seen from figure 4, which is in the nature of a quantitative 
as well as qualitative diagram of the families, I have reduced the 
number of families to eight: 
1. Nymphonidae Wilson, 1878. 5. Ammotheidae Dohrn, 1881. 
2. Pallenidae Wilson, 1878. 6. Tanystylidae Schimkewitsch, 1913. 
3. Phoxichilidiidae G. O. Sars, 1891. 7. Colossendeidae Hoek, 1881. 
4. Endeidae Norman, 1908. 8. Pycnogonidae Wilson, 1878. 
Although the traditional order of the families in large reports has 
no particular correlation with the relationships of the families, it seems 
best to retain it as a matter of convenience. 
“first tibia 
y eye tubercle 
xe 
lateral process 
chelifore: 
Scape abdomen 
chela, < 
Gs first coxa 
second COxa 
third coxa 
\\s emur 
tarsus /VWymphon grossipes(Fabr) 
A--propodus — 
i/-—terminal caw 
~~ auxiliary claws 
Figure 5.—Anatomical characters of a typical pycnogonid. 
econd tibia 
