Chap. 88.] THE AOTIPATHIES BETWEEIT AQUATIC AmMALS. 4/5 
CHAP. 87. (61.) THE MARVELLOUS PEOPEETIES OF THE 
DACTYLUS. 
Belonging also to the class of shell-fish is the dactylus/^ a 
fish so called from its strong resemblance to the human nails. 
It is the property of these fish to shine brightly in the dark, 
when all other lights are removed, and the more moisture 
they have, the brighter is the light they emit. In the mouth 
even, while they are being eaten, they give forth their light, and 
the same too when in the hands ; the very drops, in fact, that 
fall from them on the ground, or on the clothes, are of the same 
nature. Hence it is beyond a doubt, that it is a liquid that 
possesses this peculiar property, which, even in a solid body, 
would be a ground for considerable surprise. 
CHAP. 88. (62.) THE ANTIPATHIES AND SYMPATHIES THAT 
EXIST BETWEEN AQUATIC ANIMALS. 
There are also marvellous instances to be found of antipathies 
and sympathies existing between them. The mullet and the 
wolf-fish^^ are animated with a mutual hatred ; and so too, the 
conger and the murena gnaw each other's tails. The cray- 
fish has so great a dread of the polypus, that if it sees it near, 
it expires in an instant : the conger dreads the cray-fish ; 
while, again, the conger tears the body of the polypus. ]!^igidius 
informs us that the wolf-fish gnaws the tail of the mullet, and 
jT-et that, during certain months, they are on terms of friend- 
ship ; all those, however, which thus lose their tails, survive 
their misfortune. On the other hand, in addition to those which 
we have already mentioned as going in company together, an 
instance of friendship is found in the balaena and the musculus,^^ 
52 a Qy finger." The same fish that have been mentioned as " ungues," or 
"onyches," inc. 51 of the present Book. They are a multivalve shell- 
fish, Cuvier says, which live in hardened mud or the interior of rocks, into 
which they burrow cavities, from which they cannot retreat ; and they can 
only he taken by breaking the stone. They have a flavour like pepper, 
and give out a phosphorescent light. See the end of c. 51. 
53 Aristotle, Hist. Anim. B. ix. c. 3. ^lian, Hist. Anim. B. v. c. 48. 
5* Aristotle says, that the tail of the conger is bitten by the murena, 
but not that of the murena by the conger. Hardouin suggests that Pliny 
may have learned this fact from the works of Mgidius Figulus. 
55 Cuvier remarks, that in another passage, B. xi. e. 62, Pliny states that 
the musculus qui balaenam antecedit" has no teeth, but only bristles in 
its mouth. Now, in B. xxxii. c. 53, he speaks of the musculus as among 
