

434 THE AMERICAN NATURALIST. [Vou. XXXVI. 
Whether the species described by Kölliker, van Beneden, 
and McIntosh will prove to be widely different, closely related, 
or identical with that studied by Dieck, future investigations 
must decide. Suffice it to add that Dieck was quite unac- 
quainted with the descriptions of any of the other authors 
mentioned, and believed that he was describing a crab para- 
site for the first time. He shows by his descriptions that he 
knew very little of nemertean anatomy, and this fact might 
easily account for the strange anatomical peculiarities which 
he found the worms to possess. Careful comparison of his 
figures with those of van Beneden (61) and McIntosh (73) 
reveals such slight differences that we may well consider 
them as belonging to the same species; that they represent 
worms of different orders seems incredible. 
Joubin (93) has found Kolliker’s species abundant on Car- 
cinus manas at Roscoff, on the northern coast of France, and 
Giard (88), on the coast bordering the Bay of Biscay, on the 
same species of crab. Giard (p. 496) found these worms on 
almost every crab examined which carried eggs, and has 
observed the same or a very similar species on Xantho 
Jforidus. This he calls Polia xanthophila, but gives no dis- 
tinguishing peculiarities except that it is smaller in size. 
On the Challenger Expedition Willemoes-Suhm (74) found 
a small species of nemertean on the body of a species of crab 
(Nautzlograpsus minutus) which lives on the gulf weed in the 
“Sargasso Sea,” between Bermuda and the Azores. These 
little worms were only about 1-2 mm. long, but none of them 
were sexually mature. The suggestion was made that the 
nemertean inhabits the crab only when young, and that it lives 
freely on the gulf weed when mature, This form agrees with 
the other species of Carcinonemertes in possessing two large 
ocelli, although there is said to be a pair of accessory ocelli of 
extremely minute size near the proboscis. These are repre- 
sented in the figure (74). It is intimated also that the mouth 
lies behind the brain. The color of the worms was brownish. 
The stylet lies just back of the brain, and the proboscis is 
~ Very short. The figure shows indications of two pouches of 
_ accessory stylets, although these are not mentioned in the 

