ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 35 



the lobster, while the great resemblance between the shells of Lamelli- 

 branchs and Gasteropods almost justifies the belief that their mode of 

 formation is essentially the same. 



Commensalism between a Fish and a Medusa.* — In a consign- 

 ment from the Mauritius, G. Lunel found united Garanx melampygus 

 and Cramhessa palmipes. The fish stuck with the greater part of its 

 body in the apertures which are formed by the four columns uniting 

 the stomach with the nectocalyx, and traversed by the gastro-vascular 

 canals. This union could not be explained by the hypothesis that the 

 animal had sought out the other as its prey and means of nourishment. 

 For the medusa belongs to a family which possesses no proper oral 

 aperture, but only a series of microscopic pores, which can only 

 take in very finely divided nourishment, and the fish had merely 

 taken up his quarters in a natural hollow of the medusa, which was 

 only enlarged, but in no way injured, by the long residence of the 

 fish. 



It was ascertained that the fisherman had taken the two animals 

 together in that position ; and that several years ago there had been 

 seen on the coast, in a dejith of about six inches below the surface, a 

 fish of the same kind in conjunction with an anemone, and going in 

 and out of it. The anemone into which the fish had entered was 

 living, for it could be seen moving. 



Lunel arrives at the conclusion that there are certain kinds of fish 

 the fully grown individuals of which live at more or less considerable 

 depths, whilst the young, either on account of an unknown peculiarity 

 of their organization, or because they require a diet more congenial to 

 their age, ascend with particular medusae to the upper regions of the 

 sea, to find there the countless small pelagic animals on which they 

 and their hosts are nourished. It is noticeable that the fish, in order 

 to enter the medusa, must swim upon its side, therefore in a very 

 abnormal position. 



Symbiosis of Algse and Animals.-]- — K. Brandt states that the 

 occurrence of yellow cells has now been observed in the following 

 groups of animals : — Eadiolaria, Anthozoa, Hydrozoa, Foraminifera, 

 Flagellata, Ciliata, Spongias, Ctenophora, Echinoderma, Bryozoa, 

 Turbellaria, and Annelida. He is able to add the following to the 

 list of species in which they have been detected : — Reniera cratera, 

 Paralcyonium elegans, Aiptasia turgida, Echinocardium cordatum, 

 Holothuria tuhulosa (larva), Zoohothrium jpellucidum, and Eunice 

 gigantea. 



Besides yellow and brown algse, others occur also in animals. 

 Green algse have been found in numerous rhizopods and infusoria, 

 also in fresh-water sponges, hydrozoa, and turbellaria. Marine 

 sponges also contain blue-green algae, Oscillatorie^, and red and red- 

 violet Floridese. Engelmann's researches on animal chlorophyll show 

 that some modification must, however, be made of the conclusion at 



* Fol's ' Recueil Zoologique Suisse,' i. (1883) pp. 65-74 (1 pi.), 

 t Pfliiger's Arch. f. gesammt. Physiologie, 1883, pp. 445-54. Cf. this Journal, 

 ii. (1882) pp. 241, 322. 



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