304 Bibliographical Notices. 
hypothesis, however, he abandoned, another specimen of Xiphias 
gladius having been taken in the Sound in the autumn of the follow- 
ing year, on the head of which the same parasite was observed, in a 
similar cavity, but accompanied by a small Entomostracon. Assuming 
this to be either the male or the young of the larger parasite, Prof. 
Steenstrup inferred from that circumstance that the latter was a 
Crustacean; but he did not enter into any further description. 
Meanwhile Dr. Bergsde had availed himself of a stay on the shores 
of the Mediterranean for an investigation of the history of this re- 
markable animal; and the results are embodied in the paper above 
mentioned (iil. p. 87), to which is added a Latin résumé for those who 
do not understand Danish. The details of the structure are apparent 
from the very full description and the plate; and from these the 
author concludes that the proper place of the animal is amongst the 
Copepoda nearest Ergasilini, though at the same time he expresses 
the expectation that, when other similar parasites have been dis- 
covered, they will be found to constitute a new family. He gives 
besides a very minute account of the cavities in which the animal is 
found. It appears that the female fixes itself in a convenient place 
in the muciparous canals on the head; and by degrees, as the ani- — 
mal grows, the cavity grows with it. Where the canal is close to 
the surface of the skull, large cavities are formed in the bones; and 
in these cases the skin covering them and protecting the parasite is 
thin and perforated. But where the cavities containing the Phil- 
ichthys are developed in parts of the muciparous canals not in 
contact with the bones, they are generally smaller, and the integu- 
ments thick and without perforations. The cavities rarely contain 
more than one female attended by a male. In any case the cavities 
are easily observable from without; and the fishermen of Messina 
are well aware of the parasite, which they call “ Pulce.” Dr. Bergsde 
recommends the examination of other large fishes of the Mediterra- 
nean, such as the different species of Thynnus, Histiophorus, Tetra- 
pturus, Belone, as he expects that similar parasites will be found in 
them. The Philichthys affords one of the very few instances of a — 
parasitic Crustacean living entirely inside the body of its host, though 
its choice of abode, considering how much communication there is 
between the muciparous canal and the outside, is not without ana- 
logy with the habits of those numerous parasitic crustaceans met 
with in the branchial cavities of fishes. 
Dr. Bergh, who for many years past has occupied himself with the 
study, and more particularly the anatomy, of Mollusca, and pub- 
lished several valuable papers on the subject, has contributed to the 
fourth volume of the ‘ Naturhistorisk Tidsskrift’ (pp. 1 & 207) a mo- 
nograph of the family of Pleurophyllidide, embracing the substance 
of some smaller papers previously published, but containing a far 
greater quantity of new matter. The number of species described 
is seventeen, of which six are established by Dr. Bergh, belong- 
ing to the genera Pleurophyllidium, Meckel, Sancara, Bergh, and 
Camarga, Bergh. Having been favoured with specimens for dis- 
section, both from private collections and from the museums of 
