Miscellaneous. 195 



On the Propagation and Metamo)yhoses of the Suctorial Crustacea of 

 the Family CymotJioadce. By M. Schiodte, 



Having been enabled, by the liberality of the directors, to bring 

 together all the Cymothoadae existing in the principal zoological 

 museums of Scandinavia and Germany, I propose, with the colla- 

 boration of Dr. Meinert, Assistant Naturalist at the Museum of 

 Copenhagen, to publish an extensive memoir on the natural history 

 of those Crustaceans, including their biology, their morphology, and 

 the description of their genera and species. MM. Milne-Edwards 

 and Heinrich Rathke were the first to make known the young stages 

 of several Cymothoadae ; nevertheless the study of these marine 

 animals has furnished us with new facts of general interest upon 

 the subject of their metamorphoses. In my own name and that of 

 Dr. Meinert I have the honour to communicate them to the Aca- 

 demy. 



When the young issue from the ovum in the oviferous pouch of 

 the female they are perfectly smooth ; the antennae of the first pair 

 have no olfactory threads ; the antennae of the second pair, 

 the last segment of the tail, the feet, and the branchiae are entirely 

 destitute of natatory cilia. It is during the first moult, which 

 takes place before the little animal has quitted the maternal ovife- 

 rous pouch, that all these parts are developed. At the same time 

 we observe more or less considerable changes in the form of the 

 young animal, and in the configuration of its appendages, especially 

 of the tail — changes which all tend towards the same end, namely 

 to convert the creeping animal of the first stage into a swimming 

 animal. The subsequent changes which take place during a long 

 series of moults in the little Cymothoad swimming freely in the 

 sea, where it derives its nourishment from the blood or the mucus 

 of fishes, render it more and more fitted for rapid natation, at the 

 same time that the constantly advancing progress of development 

 enables it to attach itself better to the bodies of fishes. It is at 

 this period of free natation that the feet of the seventh pair are 

 developed ; the epimera of these feet, which are wanting in young 

 specimens before the second moult, begin to separate themselves from 

 the seventh segment of the body. Up to the fourth moult the feet 

 of the last pair, which are completely smooth, increase in size, re- 

 maining applied beneath the ventral surface and directed inwards, 

 in such a manner that oue cannot see them when looking at the 

 animal from above. During this period the ventral surface of the 

 females remains entirely plain, without traces of the sexual orifices 

 and oviferous pouch ; in the males, on the contrary, the correspond- 

 ing orifices become more and more visible on the ventral arch of 

 the seventh segment of the body as soon as the feet of the last pair 

 have attained perfection. 



When arrived at the adult state, the individuals of the two sexes 

 retire to copulate. The errant suctorial Cymothoadae seek a shelter 

 in the depths of the sea. The females of many parasitic Cymo- 

 thoadae attach themselves strongly to the skin or fins of fishes ; 

 others penetrate into the branchial or buccal cavity of those animals — 

 the latter hooking themselves firmly on to the surface of the tongue, 



