304 Bi'blfoynq/hical Xotices. 



hypothesis, however, he abandoned, another specimen of XipJdas 

 (jladius 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. Eergsoe 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 (iii. p. 87), to which is added a Latin resume 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. Wliere 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 PhU- 

 ichthi/s 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. Eergsoe 

 recommends the examination of other large fishes of the Mediterra- 

 nean, such as the different species of Thynnus, Ilistiophorus, Tetm- 

 2>turus, 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 commimication 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. Eergh, 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 PleiU'ophyllididfe, embracing the substance 

 of some smaller papers previously pubhshed, but containing a far 

 greater quantity of new matter. The number of species described 

 is seventeen, of which six are established by Dr. Eergh, belong- 

 ing to the genera PleuropliyJlidium, Meckel, Sancara, Eergh, and 

 Camarcja, Eergh. Having been favoured with specimens for dis- 

 section, both from private collections and from the museums of 



