SELECTED NOTES FEOM SOCIETY'S NOTE-BOOKS. 117 



is minutely serrated on the inner side, and is opposed to another 

 claw, which is immovable. Fig. 8 in PL XIV. shows one chela 

 inside the mouth and one protruded. In Fig. 7 the basal joints 

 only are drawn, so as to avoid confusion. It will be noticed that 

 the palpi have each a small tuft of hairs at the tip. The spiracle 

 is curious. In the specimen on the slide the muscles can be seen. 

 Their chief centre seems to be in the ventral plate. My 

 Dermaiiyssi were not parasites, but were found during the month of 

 February amongst moss on the top of a wall. 



H. M. J. Underhill. 



Fish Parasites (PI. XV., Figs. 3 — 5). — Caligus Rapax is 

 common on salmon when they first come into season, and may be 

 picked off the fish as they lie on the salesman's counter. I extract 

 the following from Baird's '' Student's Natural History " ; it may, 

 perhaps, prove interesting : — 



" The animals of the genus Caligus^ as established by Miiller, 

 though all agree in living as parasites upon fishes and other 

 aquatic animals, and having the organs of their mouth adapted for 

 suction instead of mastication, present so many differences among 

 themselves that it has become necessary to separate them into 

 various genera, and even into several families. In all, the mouth 

 is provided with an apparatus by means of which the little 

 creatures can puncture the skin of their hosts, and suck up the 

 nourishment derived from their bodies. They attach themselves 

 to the fishes on which they are found by a set of sharp-pointed 

 hooked claws, called foot-jaws. In general they are not immovably 

 fixed there, many of the species being able to move from one part 

 of the body to another. The eggs in the female are numerous, 

 and are generally contained in long slender ovaries, which depend 

 in a straight line from the abdomen. When hatched, the young 

 are very unlike their parent, and, like those of the Cyclopidcs^ 

 which they resemble considerably in appearance, they undergo a 

 series of changes in their progress to maturity. They are at first 

 free and unattached, swimming freely in the water, and do not 

 acquire their parasitic habits till after several moultings and 

 changes of skin. Many species have their head in the form of a 

 broad flat buckler, while the thoracic and abdominal segments are 

 uncovered. These form the restricted family of Caligidce^ with 

 the genus Caligus as the type, the species of which live on marine 

 fishes, though in the case of the salmon they are capable of living 

 for some time in fresh water also. Other species have a series of 

 lamellar plates, like the elytra, or wing cases of beetles, extending 

 along the dorsal surface of the body. These form the family 

 Paiidaridce^ with the genus Fandarus as its type, when these plates 



VOL. V. K 



