536 PYCNOGONIDA bee nGrann 
differs from Ammotheidae in the possession of a claw on appen- 
dage III. It is highly peculiar in the structure of the mouth, 
in having a long forward extension of the oculiferous tubercle 
jutting out over the proboscis, in the extreme shortness of the 
intestinal caeca and ovaries which scarcely extend into the legs, 
and in the absence of cement-glands from the fourth joint of the 
legs; these last are present only in the third joint of the pen- 
ultimate legs. A single pair of generative orifices are found on 
A B 
Fic. 284.—Rhynchothorax mediterraneus, Costa. A, Body and bases of legs ; 
B, terminal joints of palp. (After Dohrn.) 
the last legs. A second species, /. australis, Hodgson, comes 
from the Antarctic. 
Fam. 6. Nymphonidae.— Appendage I. well-developed, 
chelate; II. well-developed, usually 5-jointed; III. well- 
developed in both sexes, usually 10-jointed, the terminal joints 
with one row of denticulated spines. 
Nymphon, Fabr. (1794), about forty-five recognised species, 
of which some are but narrowly defined. Closely allied are 
Chaetonymphon, G. O. Sars (1888), including thick-set, hairy 
species, about eight in number, from the North Atlantic, Arctic, 
and Antarctic ; and Boreonymphon, G. O. Sars (1888), with one 
species (B. robustum, Bell, Fig. 276), also northern, in which the 
auxiliary claws are almost absent. Nymphon brevicaudatum, 
